Leetcode54: 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 a binary tree node. * 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;        int l = minDepth(root->left);        int r = minDepth(root->right);        if(l == 0)            return r+1;        else if(r == 0)            return l+1;        else            return min(l,r)+1;    }};