Create Day 7 Cousins in Binary Tree.cpp

Author: tusharjaiswal123

Day 7 Cousins in Binary Tree.cpp

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+PROBLEM:
+
+
+In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1.
+Two nodes of a binary tree are cousins if they have the same depth, but have different parents.
+We are given the root of a binary tree with unique values, and the values x and y of two different nodes in the tree.
+Return true if and only if the nodes corresponding to the values x and y are cousins.
+
+Example 1:
+Input: root = [1,2,3,4], x = 4, y = 3
+Output: false
+
+Example 2:
+Input: root = [1,2,3,null,4,null,5], x = 5, y = 4
+Output: true
+
+Example 3:
+Input: root = [1,2,3,null,4], x = 2, y = 3
+Output: false
+ 
+
+Note:
+
+The number of nodes in the tree will be between 2 and 100.
+Each node has a unique integer value from 1 to 100.
+
+
+SOLUTION:
+
+
+class Solution {
+public:
+    bool isCousins(TreeNode* root, int x, int y) {
+        unordered_map<int,pair<int,int>> m;
+        
+        helper(root,0,-1,m);
+        
+        if(m[x].first == m[y].first && m[x].second != m[y].second)
+            return true;
+        else
+            return false;
+    }
+    
+    void helper(TreeNode* root,int depth,int parent,unordered_map<int,pair<int,int>>& m)
+    {
+        if(root==NULL)
+            return ;
+        
+        m[root->val]={depth,parent};
+        
+        helper(root->left,depth+1,root->val,m);
+        helper(root->right,depth+1,root->val,m);
+        
+    }
+};