LeetCode: 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.

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    int minDepth(TreeNode *root) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        if (root == NULL) return 0;                int left = minDepth(root->left) + 1;        int right = minDepth(root->right) + 1;        // 叶子节点        if (left == 1 || right == 1)            return left > right ? left : right;                    return left < right ? left : right;    }};