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) {        if (root == NULL)               return 0;                    if (root->left == NULL && root->right == NULL)            return 1;                    int leftDepth = minDepth(root->left);        int rightDepth = minDepth(root->right);                if (leftDepth == 0)            return rightDepth + 1;        else if (rightDepth == 0)            return leftDepth + 1;        else            return min(leftDepth, rightDepth) + 1;    }};