Path Sum Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 r…

题目: Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move either down or right at any point in time. 题解: 这道题跟Unique Path系列是思路一样的.具…

题目: Given a binary tree, find the maximum path sum. The path may start and end at any node in the tree. For example: Given the below binary tree, 1 / \ 2 3 Return 6. 题解: 递归求解. 取当前点和左右边加和,当前点的值中最大的作为本层返回值.并在全局维护一个max.使用数组,因为是引用类型.所以在递归过程中可以保存结果. 代码如下:…

题目: Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 return…

题目: Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending or…

题目: Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero. Note: Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c) The s…

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. Example: Given nums = [2, 7, 11, 15], target = 9, Because nums[0] + nums[1] = 2…

题目: Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. The same repeated number may be chosen from C unlimited number of times. Note: All numbers (including target) w…

题目: Follow up for N-Queens problem. Now, instead outputting board configurations, return the total number of distinct solutions. 题解: 这道题跟NQueens的解法完全一样(具体解法参照N QueensN Queens leetcode java),只不过要求的返回值不同了..所以要记录的result稍微改一下就好了... 因为涉及到递归,result传进去引用类型(…

这是悦乐书的第169次更新,第171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28题(顺位题号是112).给定二叉树和整数sum,确定树是否具有根到叶路径,使得沿路径的所有值相加等于给定的sum.叶子节点是没有子节点的节点.例如: 给定以下二叉树和sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 返回true,因为存在根到叶的路径5-> 4-> 11-> 2,并且和为22. 本次解题使用的开发工具是eclips…

Design and implement a TwoSum class. It should support the following operations: add and find. add - Add the number to an internal data structure.find - Find if there exists any pair of numbers which sum is equal to the value. For example, add(1); ad…

Path Sum Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 re…

Given a binary tree, find the maximum path sum. The path may start and end at any node in the tree. For example:Given the below binary tree, 1 / \ 2 3   Return 6. 对于树,我们可以找到其左右子树中终止于根节点的最大路径值,称为最大半路径值,如果都是正数,则可以把它们以及根节点值相加,如果其中有负数,则舍弃那一边的值(即置为零).如此可以…

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2], [5,8,4,5] ] 上一道题的延伸,求出所有结果. /**…

在Path SUm 1中(http://www.cnblogs.com/hitkb/p/4242822.html) 我们采用栈的形式保存路径,每当找到符合的叶子节点,就将栈内元素输出.注意存在多条路径的情况. public List<List<Integer>> pathSum(TreeNode root, int sum) { List<List<Integer>>list=new ArrayList<>(); Stack<TreeNod…

题目: Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including target) will be…

题目: 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 / \…

题目: Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2], [5,8,4,5] ] 题解: 这道题除了要判断是否有…

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including target) will be posi…

Question 39. Combination Sum Solution 分析:以candidates = [2,3,5], target=8来分析这个问题的实现,反向思考,用target 8减2,3,5这三个数,等到target为0的时候,所减过的数就是我们要求的一个结果. Java实现: public List<List<Integer>> combinationSum(int[] candidates, int target) { List<List<Integ…

Problem Description: http://oj.leetcode.com/problems/path-sum/ Pretty easy. /** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solu…

https://oj.leetcode.com/problems/path-sum/ /** * Definition for binary tree * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public boolean hasPathSum(TreeNode root,…

1-Two Sum 题目 思路 题目中得到的信息有: 都是整数,并且可正可负,也可一个值包含多个: 只有一个正确的结果. 方法一: 最直接的思路就是两重循环遍历,时间复杂度是O(n^2),这样肯定不行. 方法二: 由于是乱序的,1)可以先排序,2)然后再遍历一遍就可以找到结果.排序的话不能再原来的基础上进行,这样就破坏了下标顺序,因此需要申请额外的空间,用于保存他们的索引,然后再该空间上进行排序.时间复杂度是[排序O(logn) + 查找O(n)],空间复杂度是O(n). /** * Note:…

Upgrade Single JAVA Component Patch Level Using SUM Tool Hi Friends, I came across few posts/threads where people are looking -How to apply patch for single component with out generating XML file in solution manager. So I thought lets write a blog on…

这里记录一下自己刷的LeetCode题目. 有些博客用英文阐述自己的思路和收获,相当于练习一下英文的表达能力. 比较好的题目有加粗. 1. Two Sum 3. Longest Substring Without Repeating Characters 5. Longest Palindromic Substring 7. Reverse Integer 9. Palindrome Number 8. String to Integer (atoi) 溢出的处理 21. Merge Two S…

题目: Implement regular expression matching with support for '.' and '*'. '.' Matches any single character. '*' Matches zero or more of the preceding element. The matching should cover the entire input string (not partial). The function prototype shoul…

Reference: http://blog.csdn.net/lbyxiafei/article/details/9375735  题目: Implement int sqrt(int x). Compute and return the square root of x. 题解: 这道题很巧妙的运用了二分查找法的特性,有序,查找pos(在这道题中pos=value),找到返回pos,找不到返回邻近值. 因为是求数x(x>=0) 的平方根, 因此,结果一定是小于等于x且大于等于0,所以用二分查…

题目: Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending or…

7-1 Maximum Subsequence Sum(25 分) Given a sequence of K integers { N​1​​, N​2​​, ..., N​K​​ }. A continuous subsequence is defined to be { N​i​​, N​i+1​​, ..., N​j​​ } where 1≤i≤j≤K. The Maximum Subsequence is the continuous subsequence which has the…

题目: The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility) P A H N A P L S I I G Y I R And then read line by line: "PAHNAP…