Leetcode #111 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.

Difficulty:Easy

/**
* 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 cal(int dep,TreeNode* root){
if(root==NULL)
return 2147483647;
if(root->left==NULL&&root->right==NULL)
return 1+dep;
return min(cal(dep+1,root->left),cal(dep+1,root->right));

}
int minDepth(TreeNode* root) {
if(root==NULL)
return 0;
if(root->left==NULL&&root->right==NULL)
return 1;
int ans = 2147483647;
ans = min(ans,cal(1,root->left));
ans = min(ans,cal(1,root->right));
return ans;

}
};