AddOneRow.cpp

AddOneRow.cpp

@@ -0,0 +1,80 @@
+// Given the root of a binary tree and two integers val and depth, add a row of nodes with value val at the given depth depth.
+
+// Note that the root node is at depth 1.
+
+// The adding rule is:
+
+// Given the integer depth, for each not null tree node cur at the depth depth - 1, create two tree nodes with value val as cur's left subtree root and right subtree root.
+// cur's original left subtree should be the left subtree of the new left subtree root.
+// cur's original right subtree should be the right subtree of the new right subtree root.
+// If depth == 1 that means there is no depth depth - 1 at all, then create a tree node with value val as the new root of the whole original tree, and the original tree is the new root's left subtree.
+
+
+
+/**
+ * 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:
+    TreeNode* addOneRow(TreeNode* root, int val, int depth) {
+
+        if(root==NULL)
+            return NULL;
+
+        if(depth==1)
+        {
+            TreeNode* newNode=new TreeNode(val);
+            newNode->left=root;
+            return newNode;
+        }
+
+        queue<TreeNode*>q;
+        q.push(root);
+
+        int height=0;
+
+        while(!q.empty())
+        {
+            height++;
+
+            if(height==depth-1)
+                break;
+
+            int n=q.size();
+            while(n--)
+            {
+                 TreeNode* node= q.front();
+                 q.pop();
+                    if(node->left)
+                    q.push(node->left);
+
+                    if(node->right)
+                    q.push(node->right);
+            }
+        }
+        int n=q.size();
+        while(n--)
+        {
+            TreeNode* node= q.front();
+                 q.pop();
+                TreeNode* newNode = new TreeNode(val);
+                newNode -> left = node -> left;
+                node -> left = newNode;
+
+
+                TreeNode* newNode2 = new TreeNode(val);
+                newNode2 -> right = node -> right;
+                node -> right = newNode2;
+
+        }
+        return root;
+    }
+};