[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.

周游二叉树即可，很简单。

/**
 * 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 curMin;
    int minDepth(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        curMin = 9999999;
        if(root==NULL)
            curMin = -1;
        DepthFirst(root,0);
        return curMin+1;
    }
    void DepthFirst(TreeNode * root,int depth)
    {
        if(depth >= curMin)
            return;
        if(root == NULL)
            return;
        if(root->left == NULL && root->right == NULL)
        {
            if(curMin > depth)
                curMin = depth;
            return;            
        }
        DepthFirst(root->left,depth + 1);
        DepthFirst(root->right,depth + 1);
    }
};