Merge pull request keshavsingh4522#803 from rajbir21-droid/lcaDsaTree

Lowest Common Ancestor of Deepest Leaves keshavsingh4522#803

CPP/Data Structures/Trees/Binary Trees/Lowest Common Ancestor of Deepest Leaves.cpp

@@ -0,0 +1,73 @@
+/*Given the root of a binary tree, return the 
+lowest common ancestor of its deepest leaves.*/
+
+//Input:-
+
+/*  0
+   / \ 
+  1   3
+   \
+    2
+*/
+
+//Output:- 2
+
+/*Explanation:- The deepest leaf node in the tree is 2, 
+                the lca of one node is itself.*/
+#include<bits/stdc++.h>
+using namespace std;
+
+ // Definition for a binary tree node.
+
+  struct TreeNode {
+      int val;
+      TreeNode *left;
+      TreeNode *right;
+      TreeNode() : val(0), left(nullptr), right(nullptr) {}
+      TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+      TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+  };
+class Solution {
+public:
+    pair<TreeNode*,int> solve(TreeNode* root){
+        if(root==NULL){
+            return {root,0};
+        }
+        auto l=solve(root->left);
+        auto r=solve(root->right);
+        //if the left level == right level then the lca is itself, as it is the deepest level.
+        if(l.second==r.second){
+            return {root,l.second+1};
+        }
+        //if left level is greater then left child is the lca
+        //vice-versa
+        if(l.second>r.second){
+            return {l.first,l.second+1};
+        }
+        return {r.first,r.second+1};
+    }
+    TreeNode* lcaDeepestLeaves(TreeNode* root) {
+        return solve(root).first;
+    }
+};
+//Printing in preorder
+void preorder(TreeNode* root){
+	 if(root==NULL){
+	 	return ;
+	 }
+	 cout<<root->val<<" ";
+	 preorder(root->left);
+	 preorder(root->right);
+
+}
+int main(){
+   	struct TreeNode* root=new TreeNode(0);
+	root->left=new TreeNode(1);
+	root->right=new TreeNode(3);
+	root->left->right=new TreeNode(2);
+	Solution obj;
+	struct TreeNode* node=obj.lcaDeepestLeaves(root);
+	preorder(node);
+  return 0;
+}
+