LeetCode111.二叉树的最小深度

题目

深度优先搜索

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

广度优先搜索

class Solution {
public:
    int minDepth(TreeNode* root) {
        if(root == NULL) return 0;
        
        queue<pair<TreeNode* ,int>>que;
        que.emplace(root,1);
        while(!que.empty()){
            TreeNode* node = que.front().first;
            int depth = que.front().second;
            que.pop();
            if(node->left == NULL && node->right == NULL) return depth;
            if(node->left != NULL) que.emplace(node->left,depth+1);
            if(node->right != NULL) que.emplace(node->right,depth+1);
        }
        return 0;
    }
    
};