Create Lowest Common Ancestor in binary tree.cpp

Top_leetcode_problems/Lowest Common Ancestor.cpp

@@ -0,0 +1,54 @@
+/**
+ * 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*> nodeToRootPath(TreeNode* root,int value){
+    if(root->val==value){
+        vector<TreeNode*>path;
+        path.push_back(root);
+        return path;
+    }
+    vector<TreeNode*>result;
+    if(root->left!=NULL){
+       result= nodeToRootPath(root->left,value);
+       if(result.size()>0){
+        result.push_back(root);
+       }
+    }
+    if(result.size()==0){
+    if(root->right!=NULL){
+        result=nodeToRootPath(root->right,value);
+        if(result.size()>0){
+        result.push_back(root);
+       }
+    }
+    }
+    return result;
+    }
+    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
+        vector<TreeNode*>path1=nodeToRootPath(root,p->val);
+        vector<TreeNode*>path2=nodeToRootPath(root,q->val);
+        int i=path1.size()-1;
+        int j=path2.size()-1;
+        TreeNode* result=NULL;
+          while(i>=0 && j>=0){
+                if(path1[i]->val==path2[j]->val){
+                        result=path1[i];
+                    }
+                    else{
+                        break;
+                    }
+                    i--;
+                    j--;
+    }
+        return result;
+    }
+};