Construct segment tree from array

Segment tree leaf node contains actual array element and its top roots are indicate child sum values.

Construct segment tree

Here given code implementation process.

// C program for
// Construct segment tree from array
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

// Display array elements
void printElement(int arr[], int n)
{
	for (int i = 0; i < n; ++i)
	{
		printf("  %d", arr[i]);
	}
}
// Returns the sum of given range element
int findSum(int *node, int first, int last, int front, int tail, int position)
{
	if (front <= first && tail >= last)
	{
		// Return range element
		return node[position];
	}
	else if (last < front || first > tail)
	{
		// When element is outside the range
		return 0;
	}
	// Find the middle position of given range
	int mid = first + (last - first) / 2;
	//  visiting the left and right subtree
	return findSum(node, first, mid, front, tail, (position *2) + 1) + findSum(node, mid + 1, last, front, tail, (position *2) + 2);
}
// Handles the request of finding sum of given range element
void nodeSum(int *node, int n, int front, int tail)
{
	if (front < 0 || tail > n - 1 || front > tail)
	{
		// Invalid range
		return;
	}
	else
	{
		int result = findSum(node, 0, n - 1, front, tail, 0);
		printf("\n Given range (%d, %d)", front, tail);
		printf("\n Sum  : %d", result);
	}
}
// Assign tree node value
int constructTree(int arr[], int front, int tail, int *node, int position)
{
	if (front == tail)
	{
		// When front and tail are similar, then set new position value
		node[position] = arr[front];
		return node[position];
	}
	// Find middle node
	int mid = front + (tail - front) / 2;
	//  visiting the left and right subtree and set new position value using recursion
	node[position] = constructTree(arr, front, mid, node, (position *2) + 1) + constructTree(arr, mid + 1, tail, node, (position *2) + 2);
	return node[position];
}
// This function are allocating the memory of segment tree
// And return segment tree
int *makeTree(int arr[], int n)
{
	// Calculate height of tree
	int x = (int)(ceil(log2(n)));
	// Get the size of tree
	int max_size = 2 *(int) pow(2, x) - 1;
	// Allocate tree node memory
	int *node = (int *) malloc(sizeof(int) *max_size);
	// Assign the element values
	constructTree(arr, 0, n - 1, node, 0);
	return node;
}
int main(int argc, char
	const *argv[])
{
	int arr[] = {
		2 , 5 , 1 , 9 , 4 , 8 , 7 , 1
	};
	int n = sizeof(arr) / sizeof(arr[0]);
	int *result = makeTree(arr, n);
	printElement(arr, n);
	// Case A
	// front = 2, tail = 5
	nodeSum(result, n, 2, 5);
	// Case B
	// front = 0, tail = 3
	nodeSum(result, n, 0, 3);
	return 0;
}

Output

  2  5  1  9  4  8  7  1
 Given range (2, 5)
 Sum  : 22
 Given range (0, 3)
 Sum  : 17
// Java Program 
// Construct segment tree from array
public class SegmentTree
{
    public int[] node;
    public int size;
    public int n;
    public SegmentTree(int arr[], int n)
    {
        this.n = n;
        this.size = treeSize();
        // Allocate memory of node
        this.node = new int[this.size];
        this.constructTree(arr, 0, n - 1, 0);
    }
    public int treeSize()
    {
        // Calculate tree height 
        int height = (int)(Math.ceil(Math.log(this.n) / Math.log(2)));

        // returns the size of tree
        return 2 * (int) Math.pow(2, height) - 1;
    }
    // Assign tree node value
    public int constructTree(int[] arr, int front, int tail, int position)
    {
        if (front == tail)
        {
            // When front and tail are similar, then set new position value
            this.node[position] = arr[front];
            return arr[front];
        }
        // Find middle node
        int mid = front + (tail - front) / 2;
        //  visiting the left and right subtree and set new position value using recursion
        this.node[position] = constructTree(arr, front, mid, (position * 2) + 1) + 
                              constructTree(arr, mid + 1, tail, (position * 2) + 2);
        return this.node[position];
    }
    // Returns the sum of given range element
    public int findSum(int first, int last, int front, int tail, int position)
    {
        if (front <= first && tail >= last)
        {
            // Return range element
            return this.node[position];
        }
        else if (last < front || first > tail)
        {
            // When element is outside the range
            return 0;
        }
        // Find the middle position of given range
        int mid = first + (last - first) / 2;
        //  visiting the left and right subtree
        return findSum(first, mid, front, tail, (position * 2) + 1) + 
              findSum(mid + 1, last, front, tail, (position * 2) + 2);
    }
    // Handles the request of finding sum of given range element
    public void nodeSum(int front, int tail)
    {
        if (front < 0 || tail > this.n - 1 || front > tail)
        {
            // Invalid range
            return;
        }
        else
        {
            int result = findSum( 0, this.n - 1, front, tail, 0);
            System.out.print("\n Given range (" + front + ", " + tail + ")");
            System.out.print("\n Sum : " + result);
        }
    }
    // Display array elements
    public void printElement(int[] arr, int n)
    {
        for (int i = 0; i < n; ++i)
        {
            System.out.print(" " + arr[i]);
        }
    }
    public static void main(String[] args)
    {
        
        int arr[] = 
        {
            2 , 5 , 1 , 9 , 4 , 8 , 7 , 1
        };
        int n = arr.length;
        SegmentTree task = new SegmentTree(arr,n);
        task.printElement(arr, n);
        // Case A
        // front = 2, tail = 5
        task.nodeSum(2, 5);
        // Case B
        // front = 0, tail = 3
        task.nodeSum(0, 3);
    }
}

Output

 2 5 1 9 4 8 7 1
 Given range (2, 5)
 Sum : 22
 Given range (0, 3)
 Sum : 17
// Include header file
#include <iostream>

#include <math.h>

using namespace std;
// C++ Program
// Construct segment tree from array
class SegmentTree
{
	public: int *node;
	int size;
	int n;
	SegmentTree(int arr[], int n)
	{
		this->n = n;
		this->size = treeSize();
		// Allocate memory of node
		this->node = new int[this->size];
		this->constructTree(arr, 0, n - 1, 0);
	}
	int treeSize()
	{
		// Calculate tree height
		int height = (int)(ceil(log(this->n) / log(2)));
		// returns the size of tree
		return (2 * (int) pow(2, height)) - 1;
	}
	// Assign tree node value
	int constructTree(int arr[], int front, int tail, int position)
	{
		if (front == tail)
		{
			// When front and tail are similar, then set new position value
			this->node[position] = arr[front];
			return arr[front];
		}
		// Find middle node
		int mid = front + (tail - front) / 2;
		//  visiting the left and right subtree and set new position value using recursion
		this->node[position] = this->constructTree(arr, front, mid, (position *2) + 1) + 
          this->constructTree(arr, mid + 1, tail, (position *2) + 2);
		return this->node[position];
	}
	// Returns the sum of given range element
	int findSum(int first, int last, int front, int tail, int position)
	{
		if (front <= first && tail >= last)
		{
			// Return range element
			return this->node[position];
		}
		else if (last < front || first > tail)
		{
			// When element is outside the range
			return 0;
		}
		// Find the middle position of given range
		int mid = first + (last - first) / 2;
		//  visiting the left and right subtree
		return this->findSum(first, mid, front, tail, (position *2) + 1) + 
          this->findSum(mid + 1, last, front, tail, (position *2) + 2);
	}
	// Handles the request of finding sum of given range element
	void nodeSum(int front, int tail)
	{
		if (front < 0 || tail > this->n - 1 || front > tail)
		// Invalid range
		{
			return;
		}
		else
		{
			int result = this->findSum(0, this->n - 1, front, tail, 0);
			cout << "\n Given range (" << front << ", " << tail << ")";
			cout << "\n Sum : " << result;
		}
	}
	// Display array elements
	void printElement(int arr[], int n)
	{
		for (int i = 0; i < n; ++i)
		{
			cout << " " << arr[i];
		}
	}
};
int main()
{
	int arr[] = {
		2 , 5 , 1 , 9 , 4 , 8 , 7 , 1
	};
	int n = sizeof(arr) / sizeof(arr[0]);
	SegmentTree task = SegmentTree(arr, n);
	task.printElement(arr, n);
	// Case A
	// front = 2, tail = 5
	task.nodeSum(2, 5);
	// Case B
	// front = 0, tail = 3
	task.nodeSum(0, 3);
	return 0;
}

Output

 2 5 1 9 4 8 7 1
 Given range (2, 5)
 Sum : 22
 Given range (0, 3)
 Sum : 17
// Include namespace system
using System;
using System.Collections.Generic;

// C# Program
// Construct segment tree from array

public class SegmentTree
{
	public int[] node;
	public int size;
	public int n;
	public SegmentTree(int[] arr, int n)
	{
		this.n = n;
		this.size = treeSize();
		// Allocate memory of node
		this.node = new int[this.size];
		this.constructTree(arr, 0, n - 1, 0);
	}
	public int treeSize()
	{
		// Calculate tree height
		int height = (int)(Math.Ceiling(Math.Log(this.n) / Math.Log(2)));
		// returns the size of tree
		return 2 * (int) Math.Pow(2, height) - 1;
	}
	// Assign tree node value
	public int constructTree(int[] arr, int front, int tail, int position)
	{
		if (front == tail)
		{
			// When front and tail are similar, then set new position value
			this.node[position] = arr[front];
			return arr[front];
		}
		// Find middle node
		int mid = front + (tail - front) / 2;
		//  visiting the left and right subtree and set new position value using recursion
		this.node[position] = constructTree(arr, front, mid, (position * 2) + 1) + 
          constructTree(arr, mid + 1, tail, (position * 2) + 2);
		return this.node[position];
	}
	// Returns the sum of given range element
	public int findSum(int first, int last, int front, int tail, int position)
	{
		if (front <= first && tail >= last)
		{
			// Return range element
			return this.node[position];
		}
		else if (last < front || first > tail)
		{
			// When element is outside the range
			return 0;
		}
		// Find the middle position of given range
		int mid = first + (last - first) / 2;
		//  visiting the left and right subtree
		return findSum(first, mid, front, tail, (position * 2) + 1) + 
          findSum(mid + 1, last, front, tail, (position * 2) + 2);
	}
	// Handles the request of finding sum of given range element
	public void nodeSum(int front, int tail)
	{
		if (front < 0 || tail > this.n - 1 || front > tail)
		{	// Invalid range
			return;
		}
		else
		{
			int result = findSum(0, this.n - 1, front, tail, 0);
			Console.Write("\n Given range (" + front + ", " + tail + ")");
			Console.Write("\n Sum : " + result);
		}
	}
	// Display array elements
	public void printElement(int[] arr, int n)
	{
		for (int i = 0; i < n; ++i)
		{
			Console.Write(" " + arr[i]);
		}
	}
	public static void Main(String[] args)
	{
		int[] arr = {
			2 , 5 , 1 , 9 , 4 , 8 , 7 , 1
		};
		int n = arr.Length;
		SegmentTree task = new SegmentTree(arr, n);
		task.printElement(arr, n);
		// Case A
		// front = 2, tail = 5
		task.nodeSum(2, 5);
		// Case B
		// front = 0, tail = 3
		task.nodeSum(0, 3);
	}
}

Output

 2 5 1 9 4 8 7 1
 Given range (2, 5)
 Sum : 22
 Given range (0, 3)
 Sum : 17
<?php
// Php Program
// Construct segment tree from array
class SegmentTree
{
	public $node;
	public $size;
	public $n;

	function __construct( & $arr, $n)
	{
		$this->n = $n;
		$this->size = $this->treeSize();
		// Allocate memory of node
		$this->node = array_fill(0, $this->size, 0);
		$this->constructTree($arr, 0, $n - 1, 0);
	}
	public	function treeSize()
	{
		// Calculate tree height
		$height = (int)(ceil(intval(log($this->n) / log(2))));
		// returns the size of tree
		return 2 * (int) pow(2, $height) - 1;
	}
	// Assign tree node value
	public	function constructTree( & $arr, $front, $tail, $position)
	{
		if ($front == $tail)
		{
			// When front and tail are similar, then set new position value
			$this->node[$position] = $arr[$front];
			return $arr[$front];
		}
		// Find middle node
		$mid = $front + intval(($tail - $front) / 2);
		//  visiting the left and right subtree and set new position value using recursion
		$this->node[$position] = $this->constructTree($arr, $front, $mid, ($position * 2) + 1) + 
          $this->constructTree($arr, $mid + 1, $tail, ($position * 2) + 2);
		return $this->node[$position];
	}
	// Returns the sum of given range element
	public	function findSum($first, $last, $front, $tail, $position)
	{
		if ($front <= $first && $tail >= $last)
		{
			// Return range element
			return $this->node[$position];
		}
		else if ($last < $front || $first > $tail)
		{
			// When element is outside the range
			return 0;
		}
		// Find the middle position of given range
		$mid = $first + intval(($last - $first) / 2);
		//  visiting the left and right subtree
		return $this->findSum($first, $mid, $front, $tail, ($position * 2) + 1) + 
          $this->findSum($mid + 1, $last, $front, $tail, ($position * 2) + 2);
	}
	// Handles the request of finding sum of given range element
	public	function nodeSum($front, $tail)
	{
		if ($front < 0 || $tail > $this->n - 1 || $front > $tail)
		// Invalid range
		{
			return;
		}
		else
		{
			$result = $this->findSum(0, $this->n - 1, $front, $tail, 0);
			echo "\n Given range (". $front .", ". $tail .")";
			echo "\n Sum : ". $result;
		}
	}
	// Display array elements
	public	function printElement( & $arr, $n)
	{
		for ($i = 0; $i < $n; ++$i)
		{
			echo " ". $arr[$i];
		}
	}
}

function main()
{
	$arr = array(2, 5, 1, 9, 4, 8, 7, 1);
	$n = count($arr);
	$task = new SegmentTree($arr, $n);
	$task->printElement($arr, $n);
	$task->nodeSum(2, 5);
	$task->nodeSum(0, 3);
}
main();

Output

 2 5 1 9 4 8 7 1
 Given range (2, 5)
 Sum : 22
 Given range (0, 3)
 Sum : 17
// Node Js Program
// Construct segment tree from array
class SegmentTree
{
	treeSize()
	{
		// Calculate tree height
		var height = parseInt((Math.ceil(parseInt(Math.log(this.n) / Math.log(2)))));
		// returns the size of tree
		return 2 * parseInt(Math.pow(2, height)) - 1;
	}
	constructor(arr, n)
	{
		this.n = n;
		this.size = this.treeSize();
		// Allocate memory of node
		this.node = Array(this.size).fill(0);
		this.constructTree(arr, 0, n - 1, 0);
	}
	// Assign tree node value
	constructTree(arr, front, tail, position)
	{
		if (front == tail)
		{
			// When front and tail are similar, then set new position value
			this.node[position] = arr[front];
			return arr[front];
		}
		// Find middle node
		var mid = front + parseInt((tail - front) / 2);
		//  visiting the left and right subtree and set new position value using recursion
		this.node[position] = this.constructTree(arr, front, mid, (position * 2) + 1) + 
          this.constructTree(arr, mid + 1, tail, (position * 2) + 2);
		return this.node[position];
	}
	// Returns the sum of given range element
	findSum(first, last, front, tail, position)
	{
		if (front <= first && tail >= last)
		{
			// Return range element
			return this.node[position];
		}
		else if (last < front || first > tail)
		{
			// When element is outside the range
			return 0;
		}
		// Find the middle position of given range
		var mid = first + parseInt((last - first) / 2);
		//  visiting the left and right subtree
		return this.findSum(first, mid, front, tail, (position * 2) + 1) +
          this.findSum(mid + 1, last, front, tail, (position * 2) + 2);
	}
	// Handles the request of finding sum of given range element
	nodeSum(front, tail)
	{
		if (front < 0 || tail > this.n - 1 || front > tail)
		// Invalid range
		{
			return;
		}
		else
		{
			var result = this.findSum(0, this.n - 1, front, tail, 0);
			process.stdout.write("\n Given range (" + front + ", " + tail + ")");
			process.stdout.write("\n Sum : " + result);
		}
	}
	// Display array elements
	printElement(arr, n)
	{
		for (var i = 0; i < n; ++i)
		{
			process.stdout.write(" " + arr[i]);
		}
	}
}

function main()
{
	var arr = [2, 5, 1, 9, 4, 8, 7, 1];
	var n = arr.length;
	var task = new SegmentTree(arr, n);
	task.printElement(arr, n);
	// Case A
	// front = 2, tail = 5
	task.nodeSum(2, 5);
	// Case B
	// front = 0, tail = 3
	task.nodeSum(0, 3);
}
main();

Output

 2 5 1 9 4 8 7 1
 Given range (2, 5)
 Sum : 22
 Given range (0, 3)
 Sum : 17
import math
#  Python 3 Program
#  Construct segment tree from array
class SegmentTree :
	
	def treeSize(self) :
		#  Calculate tree height
		height = int((math.ceil(int(math.log(self.n) / math.log(2)))))
		#  returns the size of tree
		return 2 * int(math.pow(2, height)) - 1
	
	def __init__(self, arr, n) :
		self.n = n
		self.size = self.treeSize()
		#  Allocate memory of node
		self.node = [0] * (self.size)
		self.constructTree(arr, 0, n - 1, 0)
	
	#  Assign tree node value
	def constructTree(self, arr, front, tail, position) :
		if (front == tail) :
			#  When front and tail are similar, then set new position value
			self.node[position] = arr[front]
			return arr[front]
		
		#  Find middle node
		mid = front + int((tail - front) / 2)
		#   visiting the left and right subtree and set new position value using recursion
		self.node[position] = self.constructTree(arr, front, mid, (position * 2) + 1) + \
          self.constructTree(arr, mid + 1, tail, (position * 2) + 2)
		return self.node[position]
	
	#  Returns the sum of given range element
	def findSum(self, first, last, front, tail, position) :
		if (front <= first and tail >= last) :
			#  Return range element
			return self.node[position]
		
		elif(last < front or first > tail) :
			#  When element is outside the range
			return 0
		
		#  Find the middle position of given range
		mid = first + int((last - first) / 2)
		#   visiting the left and right subtree
		return self.findSum(first, mid, front, tail, (position * 2) + 1) + \
          self.findSum(mid + 1, last, front, tail, (position * 2) + 2)
	
	#  Handles the request of finding sum of given range element
	def nodeSum(self, front, tail) :
		if (front < 0 or tail > self.n - 1 or front > tail):	
        	#  Invalid range
			return
		else :
			result = self.findSum(0, self.n - 1, front, tail, 0)
			print("\n Given range (", front ,", ", tail ,")", end = "")
			print("\n Sum : ", result, end = "")
		
	
	#  Display list elements
	def printElement(self, arr, n) :
		i = 0
		while (i < n) :
			print(" ", arr[i], end = "")
			i += 1
		
	

def main() :
	arr = [2, 5, 1, 9, 4, 8, 7, 1]
	n = len(arr)
	task = SegmentTree(arr, n)
	task.printElement(arr, n)
	#  Case A
	#  front = 2, tail = 5
	task.nodeSum(2, 5)
	#  Case B
	#  front = 0, tail = 3
	task.nodeSum(0, 3)

if __name__ == "__main__": main()

Output

  2  5  1  9  4  8  7  1
 Given range ( 2 ,  5 )
 Sum :  22
 Given range ( 0 ,  3 )
 Sum :  17
#  Ruby Program
#  Construct segment tree from array
class SegmentTree  
	# Define the accessor and reader of class SegmentTree  
	attr_reader :node, :size, :n
	attr_accessor :node, :size, :n
 
	
	def treeSize() 
		#  Calculate tree height
		height = (((Math.log(self.n) / Math.log(2))).ceil()).to_i
		#  returns the size of tree
		return 2 * (2**height).to_i - 1
	end
	def initialize(arr, n) 
		self.n = n
		self.size = self.treeSize()
		#  Allocate memory of node
		self.node = Array.new(self.size) {0}
		self.constructTree(arr, 0, n - 1, 0)
	end

	#  Assign tree node value
	def constructTree(arr, front, tail, position) 
		if (front == tail) 
			#  When front and tail are similar, then set new position value
			self.node[position] = arr[front]
			return arr[front]
		end

		#  Find middle node
		mid = front + (tail - front) / 2
		#   visiting the left and right subtree and set new position value using recursion
		self.node[position] = self.constructTree(arr, front, mid, (position * 2) + 1) +
          self.constructTree(arr, mid + 1, tail, (position * 2) + 2)
		return self.node[position]
	end

	#  Returns the sum of given range element
	def findSum(first, last, front, tail, position) 
		if (front <= first && tail >= last) 
			#  Return range element
			return self.node[position]
		elsif(last < front || first > tail) 
			#  When element is outside the range
			return 0
		end

		#  Find the middle position of given range
		mid = first + (last - first) / 2
		#   visiting the left and right subtree
		return self.findSum(first, mid, front, tail, (position * 2) + 1) + 
          self.findSum(mid + 1, last, front, tail, (position * 2) + 2)
	end

	#  Handles the request of finding sum of given range element
	def nodeSum(front, tail) 
		if (front < 0 || tail > self.n - 1 || front > tail)
		#  Invalid range
		
			return
		else 
			result = self.findSum(0, self.n - 1, front, tail, 0)
			print("\n Given range (", front ,", ", tail ,")")
			print("\n Sum : ", result)
		end

	end

	#  Display array elements
	def printElement(arr, n) 
		i = 0
		while (i < n) 
			print(" ", arr[i])
			i += 1
		end

	end

end

def main() 
	arr = [2, 5, 1, 9, 4, 8, 7, 1]
	n = arr.length
	task = SegmentTree.new(arr, n)
	task.printElement(arr, n)
	#  Case A
	#  front = 2, tail = 5
	task.nodeSum(2, 5)
	#  Case B
	#  front = 0, tail = 3
	task.nodeSum(0, 3)
end

main()

Output

 2 5 1 9 4 8 7 1
 Given range (2, 5)
 Sum : 22
 Given range (0, 3)
 Sum : 17
// Scala Program
// Construct segment tree from array
class SegmentTree(var node: Array[Int] , var size: Int , var n: Int)
{
	def this(n: Int, arr: Array[Int], size: Int)
	{
		this(Array.fill[Int](size)(0), size, n);
		this.constructTree(arr, 0, n - 1, 0);
	}
	// Assign tree node value
	def constructTree(arr: Array[Int], front: Int, tail: Int, position: Int): Int = {
		if (front == tail)
		{
			// When front and tail are similar, then set new position value
			this.node(position) = arr(front);
			return arr(front);
		}
		// Find middle node
		var mid: Int = front + ((tail - front) / 2).toInt;
		//  visiting the left and right subtree and set new position value using recursion
		this.node(position) = this.constructTree(arr, front, mid, (position * 2) + 1) + 
          this.constructTree(arr, mid + 1, tail, (position * 2) + 2);
		return this.node(position);
	}
	// Returns the sum of given range element
	def findSum(first: Int, last: Int, front: Int, tail: Int, position: Int): Int = {
		if (front <= first && tail >= last)
		{
			// Return range element
			return this.node(position);
		}
		else if (last < front || first > tail)
		{
			// When element is outside the range
			return 0;
		}
		// Find the middle position of given range
		var mid: Int = first + ((last - first) / 2).toInt;
		//  visiting the left and right subtree
		return this.findSum(first, mid, front, tail, (position * 2) + 1) + 
          this.findSum(mid + 1, last, front, tail, (position * 2) + 2);
	}
	// Handles the request of finding sum of given range element
	def nodeSum(front: Int, tail: Int): Unit = {
		if (front < 0 || tail > this.n - 1 || front > tail)
		// Invalid range
		{
			return;
		}
		else
		{
			var result: Int = this.findSum(0, this.n - 1, front, tail, 0);
			print("\n Given range (" + front + ", " + tail + ")");
			print("\n Sum : " + result);
		}
	}
	// Display array elements
	def printElement(arr: Array[Int], n: Int): Unit = {
		var i: Int = 0;
		while (i < n)
		{
			print(" " + arr(i));
			i += 1;
		}
	}
}
object Main
{
	def treeSize(n: Int): Int = {
		// Calculate tree height
		var height: Int = ((Math.ceil((Math.log(n) / Math.log(2)).toInt))).toInt;
		// returns the size of tree
		return 2 * (Math.pow(2, height)).toInt - 1;
	}
	def main(args: Array[String]): Unit = {
		var arr: Array[Int] = Array(2, 5, 1, 9, 4, 8, 7, 1);
		var n: Int = arr.length;
		var task: SegmentTree = new SegmentTree(n, arr, treeSize(n));
		task.printElement(arr, n);
		// Case A
		// front = 2, tail = 5
		task.nodeSum(2, 5);
		// Case B
		// front = 0, tail = 3
		task.nodeSum(0, 3);
	}
}

Output

 2 5 1 9 4 8 7 1
 Given range (2, 5)
 Sum : 22
 Given range (0, 3)
 Sum : 17
import Foundation
// Swift 4 Program
// Construct segment tree from array
class SegmentTree
{
	var node: [Int];
	var size: Int;
	var n: Int;

	init(_ arr: [Int], _ n: Int)
	{
		self.n = n;
      	// Calculate tree height
		let height: Int = Int((ceil(log(Float(self.n)) / log(Float(2)))));
		// returns the size of tree
		self.size = 2 * Int(pow(Double(2), Double(height))) - 1;
		// Allocate memory of node
		self.node = Array(repeating: 0, count: self.size);
		let _ = self.constructTree(arr, 0, n - 1, 0);
	}

	// Assign tree node value
	func constructTree(_ arr: [Int], _ front: Int, _ tail: Int, _ position: Int)->Int
	{
		if (front == tail)
		{
			// When front and tail are similar, then set new position value
			self.node[position] = arr[front];
			return arr[front];
		}
		// Find middle node
		let mid: Int = front + (tail - front) / 2;
		//  visiting the left and right subtree and set new position value using recursion
		self.node[position] = self.constructTree(arr, front, mid, (position * 2) + 1) 
          + self.constructTree(arr, mid + 1, tail, (position * 2) + 2);
		return self.node[position];
	}
	// Returns the sum of given range element
	func findSum(_ first: Int, _ last: Int, _ front: Int, _ tail: Int, _ position: Int)->Int
	{
		if (front <= first && tail >= last)
		{
			// Return range element
			return self.node[position];
		}
		else if (last < front || first > tail)
		{
			// When element is outside the range
			return 0;
		}
		// Find the middle position of given range
		let mid: Int = first + (last - first) / 2;
		//  visiting the left and right subtree
		return self.findSum(first, mid, front, tail, (position * 2) + 1) 
          + self.findSum(mid + 1, last, front, tail, (position * 2) + 2);
	}
	// Handles the request of finding sum of given range element
	func nodeSum(_ front: Int, _ tail: Int)
	{
		if (front < 0 || tail > self.n - 1 || front > tail)
		// Invalid range
		{
			return;
		}
		else
		{
			let result: Int = self.findSum(0, self.n - 1, front, tail, 0);
			print("\n Given range (", front ,", ", tail ,")", terminator: "");
			print("\n Sum : ", result, terminator: "");
		}
	}
	// Display array elements
	func printElement(_ arr: [Int], _ n: Int)
	{
		var i: Int = 0;
		while (i < n)
		{
			print(" ", arr[i], terminator: "");
			i += 1;
		}
	}
}
func main()
{
	let arr: [Int] = [2, 5, 1, 9, 4, 8, 7, 1];
	let n: Int = arr.count;
	let task: SegmentTree = SegmentTree(arr, n);
	task.printElement(arr, n);
	// Case A
	// front = 2, tail = 5
	task.nodeSum(2, 5);
	// Case B
	// front = 0, tail = 3
	task.nodeSum(0, 3);
}
main();

Output

  2  5  1  9  4  8  7  1
 Given range ( 2 ,  5 )
 Sum :  22
 Given range ( 0 ,  3 )
 Sum :  17
// Kotlin Program
// Construct segment tree from array
class SegmentTree
{
	var node: Array < Int > ;
	var size: Int;
	var n: Int;
	fun treeSize(): Int
	{
		// Calculate tree height
		var height: Int = (Math.ceil(Math.log(this.n.toDouble()) / Math.log(2.0))).toInt();
		// returns the size of tree
		return 2 * (Math.pow(2.0, height.toDouble())).toInt() - 1;
	}
	constructor(arr: Array < Int > , n: Int)
	{
		this.n = n;
		this.size = this.treeSize();
		// Allocate memory of node
		this.node = Array(this.size)
		{
			0
		};
		this.constructTree(arr, 0, n - 1, 0);
	}
	// Assign tree node value
	fun constructTree(arr: Array <Int> , front: Int, tail: Int, position: Int): Int
	{
		if (front == tail)
		{
			// When front and tail are similar, then set new position value
			this.node[position] = arr[front];
			return arr[front];
		}
		// Find middle node
		var mid: Int = front + (tail - front) / 2;
		//  visiting the left and right subtree and set new position value using recursion
		this.node[position] = this.constructTree(arr, front, mid, (position * 2) + 1) +
          					  this.constructTree(arr, mid + 1, tail, (position * 2) + 2);
		return this.node[position];
	}
	// Returns the sum of given range element
	fun findSum(first: Int, last: Int, front: Int, tail: Int, position: Int): Int
	{
		if (front <= first && tail >= last)
		{
			
			// Return range element
			return this.node[position];
		}
		else if (last < front || first > tail)
		{
			// When element is outside the range
			return 0;
		}
		// Find the middle position of given range
		var mid: Int = first + (last - first) / 2;
		
		//  visiting the left and right subtree
		return this.findSum(first, mid, front, tail, (position * 2) + 1) + 
          	   this.findSum(mid + 1, last, front, tail, (position * 2) + 2);
	}
	// Handles the request of finding sum of given range element
	fun nodeSum(front: Int, tail: Int): Unit
	{
		if (front < 0 || tail > this.n - 1 || front > tail)
		// Invalid range
		{
			return;
		}
		else
		{
			var result: Int = this.findSum(0, this.n - 1, front, tail, 0);
			print("\n Given range (" + front + ", " + tail + ")");
			print("\n Sum : " + result);
		}
	}
	// Display array elements
	fun printElement(arr: Array < Int > , n: Int): Unit
	{
		var i: Int = 0;
		while (i < n)
		{
			print(" " + arr[i]);
			i += 1;
		}
	}
}
fun main(args: Array <String> ): Unit
{
	var arr: Array <Int> = arrayOf(2, 5, 1, 9, 4, 8, 7, 1);
	var n: Int = arr.count();
	var task: SegmentTree = SegmentTree(arr, n);
	task.printElement(arr, n);
	// Case A
	// front = 2, tail = 5
	task.nodeSum(2, 5);
	// Case B
	// front = 0, tail = 3
	task.nodeSum(0, 3);
}

Output

 2 5 1 9 4 8 7 1
 Given range (2, 5)
 Sum : 22
 Given range (0, 3)
 Sum : 17
Implementation of segment tree


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