leetcode111. 二叉树的最小深度

递归

class Solution {
public:
    int minDepth(TreeNode* root) {
        if(!root)return 0;
        if(root->left==nullptr&&root->right==nullptr)return 1;
        int ans=INT_MAX;
        if(root->left){
            ans=min(minDepth(root->left)+1,ans);
        }
        if(root->right){
            ans=min(minDepth(root->right)+1,ans);
        }
        return ans;
    }
};