Create Lowest Common Ancestor of a Binary Tree.cpp

Author: piyush6348

Lowest Common Ancestor of a Binary Tree.cpp

@@ -0,0 +1,48 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+vector<TreeNode*> ans;
+    void getAncestor(TreeNode* temp,vector<TreeNode*> vec,TreeNode* search)
+    {
+        if(temp==NULL)
+         return ;
+        if(temp->left == search || temp->right==search)
+        {
+            vec.push_back(temp);
+            vec.push_back(search);
+            ans=vec;
+            return ;
+        }
+        vec.push_back(temp);
+        getAncestor(temp->left,vec,search);
+        getAncestor(temp->right,vec,search);
+    }
+    
+    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
+        if(root==NULL)
+            return root;
+        
+        if(root==p || root==q)
+            return root;
+        
+        TreeNode* lefty=lowestCommonAncestor(root->left,p,q);
+        TreeNode* righty=lowestCommonAncestor(root->right,p,q);
+            
+            if(lefty!=NULL && righty!=NULL)
+                return root;
+            else{
+                if(lefty!=NULL)
+                    return lefty;
+                return righty;
+            }
+        //return root;
+    }
+};