2022-09-06 Daily-Challenge

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Today I have done leetcode's September LeetCoding Challenge with cpp.

September LeetCoding Challenge 6

Description

Binary Tree Pruning

Given the root of a binary tree, return the same tree where every subtree (of the given tree) not containing a 1 has been removed.

A subtree of a node node is node plus every node that is a descendant of node.

Example 1:

img

Input: root = [1,null,0,0,1]
Output: [1,null,0,null,1]
Explanation: 
Only the red nodes satisfy the property "every subtree not containing a 1".
The diagram on the right represents the answer.

Example 2:

img

Input: root = [1,0,1,0,0,0,1]
Output: [1,null,1,null,1]

Example 3:

img

Input: root = [1,1,0,1,1,0,1,0]
Output: [1,1,0,1,1,null,1]

Constraints:

  • The number of nodes in the tree is in the range [1, 200].
  • Node.val is either 0 or 1.

Solution

class Solution {
public:
  TreeNode* pruneTree(TreeNode* root) {
    if(!root) return nullptr;
    root->left = pruneTree(root->left);
    root->right = pruneTree(root->right);
    if(!root->val && !root->left && !root->right) return nullptr;
    return root;
  }
};

// Accepted
// 30/30 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 21.01 % of cpp submissions (8.8 MB)
Algorithm