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

July LeetCoding Challenge 10

Description

Minimum Depth of Binary Tree

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

Note: A leaf is a node with no children.

Example 1:

Input: root = [3,9,20,null,null,15,7]
Output: 2

Example 2:

Input: root = [2,null,3,null,4,null,5,null,6]
Output: 5

Constraints:

• The number of nodes in the tree is in the range [0, 105].
• -1000 <= Node.val <= 1000

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  int minDepth(TreeNode* root) {
    if (root == NULL) return 0;
    queue<TreeNode*> Q;
    Q.push(root);
    int i = 0;
    while (!Q.empty()) {
      i++;
      int k = Q.size();
      for (int j = 0; j < k; ++j) {
        TreeNode* rt = Q.front();
        Q.pop();
        if (rt->left) Q.push(rt->left);
        if (rt->right) Q.push(rt->right);
        if (rt->left == NULL && rt->right == NULL) return i;
      }
    }
    return -1; //For the compiler thing. The code never runs here.
  }
};

// Accepted
// 52/52 cases passed (237 ms)
// Your runtime beats 99.27 % of cpp submissions
// Your memory usage beats 99.31 % of cpp submissions (144.4 MB)