【LeetCode】111

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.

Solution:

1.递归

/**
 * 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)
            return 0;
        else if(root->left && !root->right)
            return 1+minDepth(root->left);
        else if(!root->left && root->right)
            return 1+minDepth(root->right);
        else
            return 1+min(minDepth(root->right),minDepth(root->left));        
    }
};

2.栈，待续