Leecode 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.

 

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思路： 这道题本来没什么，wa了两次。递归的规则没有把握好。

AC代码：

/**
 * 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;
        if(root ->left == NULL && root->right == NULL) return 1;
        int ans = 1<<29;
        if(root->left)
        {
            ans = min(ans, minDepth(root->left));
        }
        if(root->right)
        {
            ans = min(ans, minDepth(root->right));
        }
        return ans + 1;
    }
};