S1mplify的博客

Generate Parentheses: Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example, given n = 3, a solution set is: [ “((()))”, “(()())”

[*Maximum Subarray*](https://leetcode.com/problems/maximum-subarray/description/): >Find the contiguous subarray within an array (containing at least one number) which has the largest sum. >For example, given

Given an input string, reverse the string word by word. For example, Given s = “the sky is blue”, return “blue is sky the”.

Length of Last Word: Given a string s consists of upper/lower-case alphabets and empty space characters ’ ‘, return the length of last word in the string. If the last word does not exist, return

Longest Palindromic Substring: Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example: Input: “babad” Output: “bab” ...

Letter Combinations of a Phone Number: Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone...

Maximum Length of Repeated Subarray: Given two integer arrays A and B, return the maximum length of an subarray that appears in both arrays. Example 1: Input: A: [1,2,3,2,1] B: [3,2,1,4

Delete and Earn Given an array nums of integers, you can perform operations on the array. In each operation, you pick any nums[i] and delete it to earn nums[i] points. After, you must delete eve

Combination Sum Given a set of candidate numbers (C) (without duplicates) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. The same repeated n...

Flatten Binary Tree to Linked List: Given a binary tree, flatten it to a linked list in-place. For example, Given 1 / \ 2 5 / \ \ 3 4 6 The flattened tree sh...

Find Pivot: Given an array of integers nums, write a method that returns the “pivot” index of this array. We define the pivot index as the index where the sum of the numbers to the left of the i

Find Pivot: Given an array of integers nums, write a method that returns the “pivot” index of this array. We define the pivot index as the index where the sum of the numbers to the left of the i

Remove Duplicates from Sorted Array: Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length. Do not allocate extra space for anoth

Longest Substring Without Repeating Characters: Given a string, find the length of the longest substring without repeating characters. Examples: Given “abcabcbb”, the answer is “abc”, which

Binary Tree Postorder Given a binary tree, return the postorder traversal of its nodes’ values. For example: Given binary tree {1,#,2,3},return [3,2,1]. Note: Recursive solution is trivi

Add Two Numbers: You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two nu

Three Sum: 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: The solution set must n

Swap Nodes in Pairs: Given a linked list, swap every two adjacent nodes and return its head. For example, Given 1->2->3->4, you should return the list as 2->1->4->3. Your algorithm shoul

Remove Element： Given an array and a value, remove all instances of that value in place and return the new length. Do not allocate extra space for another array, you must do this in place with c

Implement strStr(): Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. 执行两次遍历即可。算法复杂度在最坏的情况下不会超过O(mn)。class Solution {

Symmetric Tree： Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree [1,2,2,3,4,4,3] is symmetric: 1 / \ 2

3sum Closest: Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input wou

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 ...