Find all symmetric pairs in an array
Finding symmetric pairs in an array is a problem in programming where you need to identify pairs of elements that are symmetric with respect to each other.
Problem Statement
Given an array of pairs (2D array), find all pairs that are symmetric. A pair (a, b) is symmetric to
pair (c, d) if and only if a is equal to d and b is equal to
c.
Example
Consider the following 2D array of pairs:
arr = {
{0, 3},
{3, 6},
{9, 1},
{2, 4},
{1, 2},
{6, 3},
{7, 1},
{4, 2},
{3, 0}
}The symmetric pairs in this array are:
{0, 3}and{3, 0}{3, 6}and{6, 3}{2, 4}and{4, 2}
Idea to Solve
Iterate through the array and compare each pair (a, b) with all other pairs (c, d) to check
if they are symmetric.
Pseudocode
function symmetric_pairs(arr, size):
for i from 0 to size - 1:
for j from i + 1 to size - 1:
if arr[i][0] == arr[j][1] and arr[i][1] == arr[j][0]:
print("{" + arr[i][0] + "," + arr[i][1] + "} " + "{" + arr[j][0] + "," + arr[j][1] + "}")
// Example usage
arr = { {0, 3}, {3, 6}, {9, 1}, {2, 4}, {1, 2}, {6, 3}, {7, 1}, {4, 2}, {3, 0} }
size = size(arr)
symmetric_pairs(arr, size)Algorithm Explanation
- The
symmetric_pairsfunction takes the 2D array and its size as parameters. - It iterates through each pair
(a, b)using two nested loops. - For each pair
(a, b), it compares it with all other pairs(c, d)in the array. - If
(a, b)is symmetric to(c, d), it prints both pairs in the required format.
Code Solution
//C Program
//Find all symmetric pairs in an array
#include <stdio.h>
//Display all symmetric pairs in given array
void symmetric_pairs(int arr[][2],int size)
{
for (int i = 0; i < size; ++i)
{
for (int j = i+1; j < size; ++j)
{
//Compare pairs of array elements
if(arr[i][0]==arr[j][1] && arr[i][1]==arr[j][0] )
{
//When get Symmetric pairs
printf("\n{%d,%d} ", arr[i][0],arr[i][1]);
printf("{%d,%d}", arr[j][0],arr[j][1]);
}
}
}
}
int main()
{
//Define 2d array
int arr[][2] = {
{0, 3},
{3, 6},
{9, 1},
{2, 4},
{1, 2},
{6, 3},
{7, 1},
{4, 2},
{3, 0}
};
//Get the size of array
int size=(sizeof(arr)/sizeof(arr[0]));
symmetric_pairs(arr,size);
return 0;
}
Output
{0,3} {3,0}
{3,6} {6,3}
{2,4} {4,2}#include<iostream>
using namespace std;
/*
C++ Program
Find all symmetric pairs in an array
*/
class MyArray {
public:
//Display all symmetric pairs in given array
void symmetric_pairs(int arr[][2], int size) {
for (int i = 0; i < size; ++i) {
for (int j = i + 1; j < size; ++j) {
//Compare pairs of array elements
if (arr[i][0] == arr[j][1] && arr[i][1] == arr[j][0]) {
//When get Symmetric pairs
cout << "\n{" << arr[i][0] << "," << arr[i][1] << "} ";
cout << "{" << arr[j][0] << "," << arr[j][1] << "}";
}
}
}
}
};
int main() {
MyArray obj ;
int arr[][2] = {
{
0,
3
},
{
3,
6
},
{
9,
1
},
{
2,
4
},
{
1,
2
},
{
6,
3
},
{
7,
1
},
{
4,
2
},
{
3,
0
}
};
//Count size of array
int size = sizeof(arr) / sizeof(arr[0]);
obj.symmetric_pairs(arr, size);
return 0;
}
Output
{0,3} {3,0}
{3,6} {6,3}
{2,4} {4,2}/*
Java Program
Find all symmetric pairs in an array
*/
public class MyArray {
//Display all symmetric pairs in given array
public void symmetric_pairs(int [][]arr,int size)
{
for (int i = 0; i < size; ++i)
{
for (int j = i+1; j < size; ++j)
{
//Compare pairs of array elements
if(arr[i][0]==arr[j][1] && arr[i][1]==arr[j][0] )
{
//When get Symmetric pairs
System.out.print("\n"+arr[i][0]+","+arr[i][1]+"} ");
System.out.print("{"+arr[j][0]+","+arr[j][1]+"}" );
}
}
}
}
public static void main(String[] args)
{
MyArray obj = new MyArray();
//Define array elements
int [][]arr = {
{0, 3},
{3, 6},
{9, 1},
{2, 4},
{1, 2},
{6, 3},
{7, 1},
{4, 2},
{3, 0}
};
//Count size of array
int size=arr.length;
obj.symmetric_pairs(arr,size);
}
}
Output
{0,3} {3,0}
{3,6} {6,3}
{2,4} {4,2}using System;
/*
C# Program
Find all symmetric pairs in an array
*/
public class MyArray {
//Display all symmetric pairs in given array
public void symmetric_pairs(int[,] arr, int size) {
for (int i = 0; i < size; ++i) {
for (int j = i + 1; j < size; ++j) {
//Compare pairs of array elements
if (arr[i,0] == arr[j,1] && arr[i,1] == arr[j,0]) {
Console.Write("\n{" + arr[i,0] + "," + arr[i,1] + "} ");
Console.Write("{" + arr[j,0] + "," + arr[j,1] + "}");
}
}
}
}
public static void Main(String[] args) {
MyArray obj = new MyArray();
//Define array elements
int[,] arr = {
{
0,
3
},
{
3,
6
},
{
9,
1
},
{
2,
4
},
{
1,
2
},
{
6,
3
},
{
7,
1
},
{
4,
2
},
{
3,
0
}
};
//Count size of array
int size = arr.GetLength(0);
obj.symmetric_pairs(arr, size);
}
}
Output
{0,3} {3,0}
{3,6} {6,3}
{2,4} {4,2}<?php
/*
Php Program
Find all symmetric pairs in an array
*/
class MyArray {
//Display all symmetric pairs in given array
public function symmetric_pairs($arr, $size) {
for ($i = 0; $i < $size; ++$i) {
for ($j = $i + 1; $j < $size; ++$j) {
//Compare pairs of array elements
if ($arr[$i][0] == $arr[$j][1] && $arr[$i][1] == $arr[$j][0]) {
//When get Symmetric pairs
echo("\n{". $arr[$i][0] .",". $arr[$i][1] ."} ");
echo("{". $arr[$j][0] .",". $arr[$j][1] ."}");
}
}
}
}
}
function main() {
$obj = new MyArray();
//Define array elements
$arr = array(
array(0, 3),
array(3, 6),
array(9, 1),
array(2, 4),
array(1, 2),
array(6, 3),
array(7, 1),
array(4, 2),
array(3, 0)
);
//Count size of array
$size = count($arr);
$obj->symmetric_pairs($arr, $size);
}
main();
Output
{0,3} {3,0}
{3,6} {6,3}
{2,4} {4,2}/*
Node Js Program
Find all symmetric pairs in an array
*/
class MyArray {
//Display all symmetric pairs in given array
symmetric_pairs(arr, size) {
for (var i = 0; i < size; ++i) {
for (var j = i + 1; j < size; ++j) {
//Compare pairs of array elements
if (arr[i][0] == arr[j][1] && arr[i][1] == arr[j][0]) {
//When get Symmetric pairs
process.stdout.write("\n{" + arr[i][0] + "," + arr[i][1] + "} ");
process.stdout.write("{" + arr[j][0] + "," + arr[j][1] + "}");
}
}
}
}
}
function main(args) {
var obj = new MyArray();
//Define array elements
var arr = [
[0, 3],
[3, 6],
[9, 1],
[2, 4],
[1, 2],
[6, 3],
[7, 1],
[4, 2],
[3, 0]
];
//Count size of array
var size = arr.length;
obj.symmetric_pairs(arr, size);
}
main();
Output
{0,3} {3,0}
{3,6} {6,3}
{2,4} {4,2}# Python 3 Program
# Find all symmetric pairs in an array
class MyArray :
# Display all symmetric pairs in given array
def symmetric_pairs(self, arr, size) :
i = 0
while (i < size) :
j = i + 1
while (j < size) :
# Compare pairs of array elements
if (arr[i][0] == arr[j][1] and arr[i][1] == arr[j][0]) :
print("\n(", arr[i][0] ,",", arr[i][1] ,") ", end = "")
print("(", arr[j][0] ,",", arr[j][1] ,")", end = "")
j += 1
i += 1
def main() :
obj = MyArray()
arr = [
[0, 3],
[3, 6],
[9, 1],
[2, 4],
[1, 2],
[6, 3],
[7, 1],
[4, 2],
[3, 0]
]
size = len(arr)
obj.symmetric_pairs(arr, size)
if __name__ == "__main__":
main()
Output
( 0 , 3 ) ( 3 , 0 )
( 3 , 6 ) ( 6 , 3 )
( 2 , 4 ) ( 4 , 2 )# Ruby Program
# Find all symmetric pairs in an array
class MyArray
# Display all symmetric pairs in given array
def symmetric_pairs(arr, size)
i = 0
while (i < size)
j = i + 1
while (j < size)
# Compare pairs of array elements
if (arr[i][0] == arr[j][1] && arr[i][1] == arr[j][0])
print("(", arr[i][0] ,",", arr[i][1] ,") ")
print("(", arr[j][0] ,",", arr[j][1] ,")\n")
end
j += 1
end
i += 1
end
end
end
def main()
obj = MyArray.new()
arr = [
[0, 3],
[3, 6],
[9, 1],
[2, 4],
[1, 2],
[6, 3],
[7, 1],
[4, 2],
[3, 0]
]
size = arr.length
obj.symmetric_pairs(arr, size)
end
main()
Output
(0,3) (3,0)
(3,6) (6,3)
(2,4) (4,2)
/*
Scala Program
Find all symmetric pairs in an array
*/
class MyArray {
//Display all symmetric pairs in given array
def symmetric_pairs(arr: Array[Array[Int]], size: Int): Unit = {
var i: Int = 0;
while (i < size) {
var j: Int = i + 1;
while (j < size) {
//Compare pairs of array elements
if (arr(i)(0) == arr(j)(1) && arr(i)(1) == arr(j)(0)) {
print("\n(" + arr(i)(0) + "," + arr(i)(1) + ") ");
print("(" + arr(j)(0) + "," + arr(j)(1) + ")");
}
j += 1;
}
i += 1;
}
}
}
object Main {
def main(args: Array[String]): Unit = {
val obj: MyArray = new MyArray();
val arr: Array[Array[Int]] = Array(
Array(0, 3),
Array(3, 6),
Array(9, 1),
Array(2, 4),
Array(1, 2),
Array(6, 3),
Array(7, 1),
Array(4, 2),
Array(3, 0));
val size: Int = arr.length;
obj.symmetric_pairs(arr, size);
}
}
Output
(0,3) (3,0)
(3,6) (6,3)
(2,4) (4,2)/*
Swift Program
Find all symmetric pairs in an array
*/
class MyArray {
//Display all symmetric pairs in given array
func symmetric_pairs(_ arr: [
[Int]
], _ size: Int) {
var i: Int = 0;
while (i < size) {
var j: Int = i + 1;
while (j < size) {
//Compare pairs of array elements
if (arr[i][0] == arr[j][1] && arr[i][1] == arr[j][0]) {
print("\n(", arr[i][0] ,",", arr[i][1] ,") ", terminator: "");
print("(", arr[j][0] ,",", arr[j][1] ,")", terminator: "");
}
j += 1;
}
i += 1;
}
}
}
func main() {
let obj: MyArray = MyArray();
let arr: [
[Int]
] = [
[0, 3],
[3, 6],
[9, 1],
[2, 4],
[1, 2],
[6, 3],
[7, 1],
[4, 2],
[3, 0]
];
let size: Int = arr.count;
obj.symmetric_pairs(arr, size);
}
main();
Output
( 0 , 3 ) ( 3 , 0 )
( 3 , 6 ) ( 6 , 3 )
( 2 , 4 ) ( 4 , 2 )Time Complexity
The algorithm compares each pair with all other pairs, resulting in a nested loop structure. Therefore, the time
complexity of the algorithm is O(n^2), where n is the size of the 2D array.
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