# Check for continuous binary tree in swift

Swift program for Check for continuous binary tree. Here problem description and other solutions.

``````import Foundation
/*
Swift 4 program for
Check if binary tree is continuous tree
Using recursion
*/
// Binary Tree Node
class TreeNode
{
var data: Int;
var left: TreeNode? ;
var right: TreeNode? ;
init(_ data: Int)
{
// Set node value
self.data = data;
self.left = nil;
self.right = nil;
}
}
class BinaryTree
{
var root: TreeNode? ;
init()
{
self.root = nil;
}
func absValue(_ num: Int) -> Int
{
if (num < 0)
{
return -num;
}
return num;
}
// Check tree is continuous or not
func isContinuous(_ node: TreeNode? ) -> Bool
{
if (node  != nil)
{
if ((node!.left  != nil &&
self.absValue(node!.data - node!.left!.data)  != 1) ||
(node!.right  != nil &&
self.absValue(node!.data - node!.right!.data)  != 1))
{
// Case
// When fail continuous tree rule
return false;
}
if (self.isContinuous(node!.left) &&
self.isContinuous(node!.right))
{
return true;
}
// When node value is not satisfied
//  continuous tree properties
return false;
}
return true;
}
static func main()
{
// Create new tree
let tree: BinaryTree = BinaryTree();
/*
Binary Tree
------------
5
/   \
4     4
/     /  \
3     5    3
\
2

*/
tree.root = TreeNode(5);
tree.root!.left = TreeNode(4);
tree.root!.right = TreeNode(4);
tree.root!.left!.left = TreeNode(3);
tree.root!.right!.right = TreeNode(3);
tree.root!.right!.left = TreeNode(5);
tree.root!.left!.left!.right = TreeNode(2);
if (tree.isContinuous(tree.root) == true)
{
print("Continuous Tree ");
}
else
{
print("Not Continuous Tree ");
}
// Case 2
/*
5
/   \
4     4
/     /  \
3     5    3
\
1  <--- change value

*/
tree.root!.left!.left!.right!.data = 1;
if (tree.isContinuous(tree.root) == true)
{
print("Continuous Tree ");
}
else
{
print("Not Continuous Tree ");
}
}
}
BinaryTree.main();``````

Output

``````Continuous Tree
Not Continuous Tree``````

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