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[LeetCode]143. Reorder List 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.me/ 题目地址:https://leetcode.com/problems/reorder-list/description/ 题目描述: Given a singly linked list L: L0→L1→-→Ln-1→Ln, reorder it to: L0→Ln…
Combination Sum Combination Sum Total Accepted: 25850 Total Submissions: 96391 My Submissions Question Solution 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…
全排列问题.经常使用的排列生成算法有序数法.字典序法.换位法(Johnson(Johnson-Trotter).轮转法以及Shift cursor cursor* (Gao & Wang)法. [题目] Given a collection of numbers, return all possible permutations. For example, [1,2,3] have the following permutations: [1,2,3], [1,3,2], [2,1,3], [2…
以前从来没有写过解题报告,只是看到大肥羊河delta写过不少.最近想把写博客的节奏给带起来,所以就挑一个比较容易的题目练练手. 原题链接 https://leetcode.com/problems/course-schedule/ 题目大意 有n个课程,编号分别是0到n-1.我们的目标是修完所有课程.然而有些课程有前置课程的,我们必须修完前置课程才能修该门课程.题目给了我们课程之间的前置关系,让我们判断是否能修完所有课程. 题目原型 这个题目的描述简单粗暴,我们不难发现,其实是给了我们一个有向图…
Sort ColorsGiven an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue. Here, we will use the integers 0, 1, and 2 to represent the color red, wh…
Given a singly linked list L: L0→L1→-→Ln-1→Ln, reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→- You must do this in-place without altering the nodes' values. For example, Given {1,2,3,4}, reorder it to {1,4,2,3}. /** * Definition for singly-linked list. * clas…
Permutation Sequence https://oj.leetcode.com/problems/permutation-sequence/ The set [1,2,3,…,n] contains a total of n! unique permutations. By listing and labeling all of the permutations in order, We get the following sequence (ie, for n = 3): "123&…
Interleaving StringGiven s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2. For example,Given:s1 = "aabcc",s2 = "dbbca", When s3 = "aadbbcbcac", return true.When s3 = "aadbbbaccc", return false.…
Scramble String Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively. Below is one possible representation of s1 = "great": great / \ gr eat / \ / \ g r e at / \ a t To scramble the s…
Gas Station There are N gas stations along a circular route, where the amount of gas at station i is gas[i]. You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to its next station (i+1). You begin the journ…
Given a string s, partition s such that every substring of the partition is a palindrome. Return all possible palindrome partitioning of s. For example, given s = "aab",Return [    ["aa","b"],    ["a","a",…
Sort List Sort a linked list in O(n log n) time using constant space complexity. 使用Merge Sort, 空间复杂度是 O(logN) 因为使用了栈空间. SOLUTION 1: 使用Merge Sort来解决问题. 为什么不用QuickSort? 因为随机访问对于链表而言太耗时,而heap sort不可行. 注意,Find Mid用了2种解法.或者是让Fast提前结束,或是让Fast先走一步,目的就是要取得中间…
Wildcard MatchingImplement wildcard pattern matching with support for '?' and '*'. '?' Matches any single character.'*' Matches any sequence of characters (including the empty sequence). The matching should cover the entire input string (not partial)…
Maximal RectangleGiven a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area. Show TagsHave you met this question in a real interview? Yes  NoDiscussSOLUTION 1: public class Solution { public i…
Merge IntervalsGiven a collection of intervals, merge all overlapping intervals. For example,Given [1,3],[2,6],[8,10],[15,18],return [1,6],[8,10],[15,18]. SOLUTION 1: 1. 先使用Comparator 的匿名类对intervels进行排序. 2. 把Intervals遍历一次,依次一个一个merge到第1个interval. 把第1…
A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in t…
[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 o…
Largest Number Given a list of non negative integers, arrange them such that they form the largest number. For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330. Note: The result may be very large, so you need to return a string…
Next Permutation Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers. If such arrangement is not possible, it must rearrange it as the lowest possible order (ie, sorted in ascending orde…
Valid Parentheses Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" a…
Sqrt(x) Implement int sqrt(int x). Compute and return the square root of x. SOLUTION 1: 参见:二分法总结,以及模板:http://t.cn/RZGkPQc public class Solution { public int sqrt(int x) { if (x == 1 || x == 0) { return x; } int left = 1; int right = x; while (left <…
Distinct Subsequences Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without di…
Valid Palindrome Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man, a plan, a canal: Panama" is a palindrome."race a car" is not a palindrome. Note:Have you…
Edit Distance Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.) You have the following 3 operations permitted on a word: a) Insert a characterb) Delete a chara…
Maximum Subarray Find the contiguous subarray within an array (containing at least one number) which has the largest sum. For example, given the array [−2,1,−3,4,−1,2,1,−5,4],the contiguous subarray [4,−1,2,1] has the largest sum = 6. SOLUTION 1: 采用滑…
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             / \        …
N-Queens II (LEVEL 4 难度级别,最高级5) Follow up for N-Queens problem.…
Reverse Integer Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 click to show spoilers. SOLUTION 1: 注意越界后返回0.先用long来计算,然后,把越界的处理掉. public class Solution { public int reverse(int x) { long ret = 0; while (x !…
Partition List Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x. You should preserve the original relative order of the nodes in each of the two partitions. For example,Given…
Symmetric Tree Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree is symmetric: 1   / \  2   2 / \ / \3  4 4  3But the following is not:    1   / \  2   2   \   \   3    3Note:…