Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. 这道题让我们求一棵二叉树的所有左子叶的和,那么看到这道题我们知道这肯定是考二叉树的遍历问题,那么最简洁的写法肯定是用递归,由于我们只需要累加左子叶…

原题链接在这里:https://leetcode.com/problems/sum-of-left-leaves/ 题目: Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. 题解: DFS, 若r…

404. 左叶子之和 404. Sum of Left Leaves LeetCode404. Sum of Left Leaves 题目描述 计算给定二叉树的所有左叶子之和. 示例: 3 / \ 9 20 / \ 15 7 在这个二叉树中,有两个左叶子,分别是 9 和 15,所以返回 24. Java 实现 TreeNode 结构 class TreeNode { int val; TreeNode left; TreeNode right; TreeNode(int x) { val = x…

404. Sum of Left Leaves [题目]中文版  英文版 /** * 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 sumOfLeftLea…

404. Sum of Left Leaves Easy Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. package leetcode.easy; /** * Definition for…

LeetCode--Sum of Two Integers Question Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example: Given a = 1 and b = 2, return 3. Solution 异或操作有累加的效果,但是没有进位的效果.什么时候进位呢? 同时为1的时候进位,往前进一位,所以用交集操作,再移位,表示进位.…

Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. 题目标签:Tree 这道题目给了我们一个二叉树,让我们找到所有左子叶之和.这里需要另外一个function - sumLeftLeaves 还要一…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目大意 题目大意 解题方法 递归 迭代 日期 [LeetCode] 题目地址:https://leetcode.com/problems/sum-of-left-leaves/ Difficulty: Easy 题目大意 Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \…

Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. /** * Definition for a binary tree node. * public class TreeNode { * int…

Find the sum of all left leaves in a given binary tree. Example:     3    / \   9  20     /  \    15   7   There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. 思路:还是递归.仔细看代码,体会递归的设计方法.…

这是悦乐书的第217次更新,第230篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第85题(顺位题号是404).找到给定二叉树中所有左叶的总和.例如: 二叉树中有两个左叶,分别为9和15. 返回24. 3 / \ 9 20 / \ 15 7 本次解题使用的开发工具是eclipse,jdk使用的版本是1.8,环境是win7 64位系统,使用Java语言编写和测试. 02 第一种解法 使用递归. 特殊情况:当root为null时,直接返回0. 正常情况:定义一个变量su…

Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. # Definition for a binary tree node. # class TreeNode(object): # def __in…

题目: Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. 分析: 给定一颗二叉树,求左叶子节点的和. 重点在于如何判断左叶子节点,如果一个节点的left存在,且left的left和right都为空…

问题 该文章的最新版本已迁移至个人博客[比特飞],单击链接 https://www.byteflying.com/archives/4084 访问. 计算给定二叉树的所有左叶子之和. 3      / \    9  20   /       \ 15       7 在这个二叉树中,有两个左叶子,分别是 9 和 15,所以返回 24 Find the sum of all left leaves in a given binary tree. 3      / \    9  20   /  …

------------------------------------------------------------------- 分两种情况: 1.当前节点拥有左孩子并且左孩子是叶子节点:左孩子值+右孩子子树遍历统计2.不符合上面那种情况的从当前节点劈开为两颗子树分别统计相加即可 AC代码: /** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * Tre…

#-*- coding: UTF-8 -*- # Definition for a binary tree node.# class TreeNode(object):#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution(object):        def dfs(self,root,isLeft):      …

1.题目描述 2.问题分析 对于每个节点,如果其左子节点是叶子,则加上它的值,如果不是,递归,再对右子节点递归即可. 3.代码 int sumOfLeftLeaves(TreeNode* root) { if (root == NULL) ; ; if (root->left != NULL) { if (root->left->left == NULL && root->left->right == NULL) ans += root->left-&g…

弄个flag记录是不是左节点就行 int res = 0; public int sumOfLeftLeaves(TreeNode root) { if (root==null) return res; leftSum(root,false); return res; } private void leftSum(TreeNode root,boolean flag) { if (root.left==null&&root.right==null&&flag) res+=r…

Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. 计算给定二叉树的所有左叶子之和. 示例: 3 / \ 9 20 / \ 15 7 在这个二叉树中,有两个左叶子,分别是 9 和 15,所以返回 2…

Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example: Given a = 1 and b = 2, return 3. Credits:Special thanks to @fujiaozhu for adding this problem and creating all test cases. 这道题是CareerCup上的一道原题,难道…

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 which represents the number 123. Find the total sum of all root-to-leaf numbers. For example, 1 / \ 2 3…

原题链接在这里:https://leetcode.com/problems/sum-of-two-integers/ 题目: Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example:Given a = 1 and b = 2, return 3. 题解: 两个数79和16 相加,不考虑进位相加得85, 只考虑进位进位是10, 85+10 = 95…

Find the sum of all left leaves in a given binary tree. 左树的值(9+15=24) /** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { publi…

Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. /** * Definition for a binary tree node. * public class TreeNode { * int…

原题地址:http://oj.leetcode.com/problems/sum-root-to-leaf-numbers/ 题意: Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 which represents the number 123. Fin…

Sum 系列题解 Two Sum题解 题目来源:https://leetcode.com/problems/two-sum/description/ Description Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one sol…

［抄题］: Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. [暴力解法]: 时间分析: 空间分析: ［奇葩输出条件］: ［奇葩corner case］: ［思维问题］: root.left ro…

LeetCode很喜欢sum,里面sum题一堆. 1.Two Sum Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. E…

Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example: Given a = 1 and b = 2, return 3. 转自https://discuss.leetcode.com/topic/49771/java-simple-easy-understand-solution-with-explanation/2,注意里面对于减法的讲解 h…

Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24. Solution 1:BFS /** * Definition for a binary tree node. * public class Tr…