LeetCode 366. Find Leaves of Binary Tree

实质就是求每个节点的最大深度。用一个hash表记录，最后输出。

class Solution {
public:unordered_map<TreeNode *,int> hash; // record the level from bottom
    vector<vector<int>> findLeaves(TreeNode* root) {vector<vector<int>> res;dfs(root);//for (auto x:hash) cout << x.first->val << ' ' << x.second << endl;for (int i=1;i<=hash[root];++i){vector<int> tmp;for (auto x:hash){if (x.second==i)tmp.push_back(x.first->val);}res.push_back(tmp);}return res;}int dfs(TreeNode *root){if (root==NULL) return 0;int depth=max(dfs(root->left),dfs(root->right))+1;hash[root] = depth;return depth;}
};

其实可以不用hash表，每次深度比vector.size()大的时候新建一个vector，这样节省了空间。

类似的方法在别的题里也有应用。

class Solution {
public:vector<vector<int>> res;vector<vector<int>> findLeaves(TreeNode* root) {dfs(root);return res;}int dfs(TreeNode *root){if (root==NULL) return 0;int depth=max(dfs(root->left),dfs(root->right))+1;if (depth>res.size()) res.push_back(vector<int>());res[depth-1].push_back(root->val);return depth;}
};

转载于:https://www.cnblogs.com/hankunyan/p/9583602.html

LeetCode 366. Find Leaves of Binary Tree相关推荐

【LeetCode】Minimum Depth of Binary Tree 二叉树的最小深度 java
[LeetCode]Minimum Depth of Binary Tree Given a binary tree, find its minimum depth. The minimum dept ...
LeetCode: 104. Maximum Depth of Binary Tree
题目 Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the l ...
leetcode 662. Maximum Width of Binary Tree | 662. 二叉树最大宽度（BFS）
题目 https://leetcode.com/problems/maximum-width-of-binary-tree/ 题解本题思路来源于二叉树的层序遍历. 层序遍历类似问题:leetcode ...
LeetCode 662. Maximum Width of Binary Tree
原题链接在这里:https://leetcode.com/problems/maximum-width-of-binary-tree/ 题目: Given a binary tree, write a ...
LeetCode 111. Minimum Depth of Binary Tree （二叉树最小的深度）
Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shor ...
LeetCode 297 Serialize and Deserialize Binary Tree
题目描述 Serialization is the process of converting a data structure or object into a sequence of bits s ...
Leetcode | Minimum/Maximum Depth of Binary Tree
Minimum Depth of Binary Tree Given a binary tree, find its minimum depth. The minimum depth is the n ...
LeetCode：104_Maximum Depth of Binary Tree | 二叉树的最大深度 | Easy
要求:求二叉树的深度(二叉树的深度为最远叶子节点到根节点的距离,即根节点到最远叶子节点的距离) Given a binary tree, find its maximum depth.The maxi ...
leetcode 606. Construct String from Binary Tree | 606. 根据二叉树创建字符串
题目 https://leetcode-cn.com/problems/construct-string-from-binary-tree/ 题解当右子树非空时,不管有没有左子树,一定要用()将左子 ...

LeetCode 366. Find Leaves of Binary Tree

LeetCode 366. Find Leaves of Binary Tree相关推荐

最新文章

热门文章