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 == 0)            return 0;        int a = minDepth(root->left);        int b = minDepth(root->right);        if(a*b != 0)            return min(a,b) + 1;        else if(a == 0)            return b + 1;        else            return a + 1;    }};