Merge pull request #627 from vishwajeet-hogale/main

Oct 5th leetcode problem : Add one row to tree

Trees/addOneRowToTree.cpp

@@ -1,3 +1,83 @@
+
+#include<bits/stdc++.h>
+#include<iostream>
+using namespace std;
+struct TreeNode{
+    int val;
+    TreeNode *left,*right;
+    TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+};
+
+/*
+
+    Intuition
+        Use queues to peform bfs and traverse the tree. When you reach depth - 1 ,
+        perform the operations mentioned in the question
+
+    Approach
+        There are two cases when you reach depth - 1 using bfs.
+        Assume curr is the current node at depth - 1
+
+            * curr->left != NULL
+            * curr->left == NULL
+        The code handles the above two cases.
+        There is also one edge case that the code can't handle.
+        If the depth is 1 which means we need to add the new_node as the root node.
+
+        So we have to write a seperate code to handle depth = 1 case.
+*/
+TreeNode* addOneRow(TreeNode* root, int val, int depth) {
+
+        int d = 0;
+        if(d == (depth - 1)){
+            TreeNode *new_node = new TreeNode(val);
+            new_node->left = root;
+            root = new_node;
+            return root; 
+        }
+        queue<TreeNode*> q;
+        q.push(root);
+        while(!q.empty()){
+            int size = q.size();
+            d++;
+            for(int i=0;i<size;i++){
+                TreeNode *curr = q.front();
+                q.pop();
+                if(!curr)
+                    continue;
+                if(d == (depth - 1)){
+                    TreeNode *new_node = new TreeNode(val);
+                    TreeNode *new_node1 = new TreeNode(val);
+                    if(curr->left){
+                        TreeNode *temp = curr->left;
+                        new_node->left = temp;
+                        curr->left = new_node;
+                    }
+                    else{
+                        curr->left = new_node;
+                    }
+                    if(curr->right){
+                        TreeNode *temp = curr->right;
+                        new_node1->right = temp;
+                        curr->right = new_node1;
+                    }
+                    else{
+                        curr->right = new_node1;
+                    }
+
+                }
+                if(curr->left)
+                    q.push(curr->left);
+                if(curr->right)
+                    q.push(curr->right);
+
+            }
+            if(d == (depth-1))
+                break;
+        }
+        return root;
+}
+=======
 /*
 
 623. Add One Row to Tree
@@ -59,4 +139,5 @@ class Solution {
         dfs(root,val,depth,1);
         return root;
     }
-};
+};
+