xunalove的博客

题目Given two arrays, write a function to compute their intersection.Example: Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].Note:Each element in the result must be unique.The result c...

题目Given two arrays, write a function to compute their intersection.Example: Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2, 2].Note:Each element in the result should appear as many tim...

题目You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 stones. The one who removes the last stone will be...

题目Given a string, find the first non-repeating character in it and return it’s index. If it doesn’t exist, return -1.Examples:s = "leetcode"return 0.s = "loveleetcode",return 2.Note: You ...

题目You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?Note: Given n will be a posi...

题目You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent h...

题目Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.Example:Given nums = [-2, 0, 3, -5, 2, -1]sumRange(0, 2) -> 1sumRange(2, 5) -> -1...

题目Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a greed factor gi, which is the minimum size of a...

题目Write an algorithm to determine if a number is “happy”.A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squar...

题目Description:Count the number of prime numbers less than a non-negative number, n.题意小于n的素数的个数。题解 普通的筛法求素数超时。 提示中的一种解法：厄拉多塞筛法（https://leetcode.com/problems/count-primes/hints/）西元前2...

题目Given two strings s and t, write a function to determine if t is an anagram of s. s = "anagram", t = "nagaram", return true. s = "rat", t = "car", return false. 题意判断 t 是否是由 s 颠倒顺序构成的...

题目Given a non-empty array of non-negative integers nums, the degree of this array is defined as the maximum frequency of any one of its elements.Your task is to find the smallest possible length o...

题目Given a non-empty 2D array grid of 0’s and 1’s, an island is a group of 1’s (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are su...

题目On a staircase, the i-th step has some non-negative cost cost[i] assigned (0 indexed).Once you pay the cost, you can either climb one or two steps. You need to find minimum cost to reach the top...

题目Given an array of 2n integers, your task is to group these integers into n pairs of integer, say (a1, b1), (a2, b2), …, (an, bn) which makes sum of min(ai, bi) for all i from 1 to n as large as po...

题目Given a 2D integer matrix M representing the gray scale of an image, you need to design a smoother to make the gray scale of each cell becomes the average gray scale (rounding down) of all the 8 s...

题目Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.push(x) -- Push element x onto stack.pop() -- Removes the element on top of the stack.top() -- ...

题目Implement the following operations of a stack using queues.push(x) – Push element x onto stack.pop() – Removes the element on top of the stack.top() – Get the top element.empty() – Return wh...

题目Implement the following operations of a queue using stacks.push(x) -- Push element x to the back of queue.pop() -- Removes the element from in front of queue.peek() -- Get the front element.e...

题目You are given two arrays (without duplicates) nums1 and nums2 where nums1’s elements are subset of nums2. Find all the next greater numbers for nums1’s elements in the corresponding places of nums...

题目You’re now a baseball game point recorder.Given a list of strings, each string can be one of the 4 following types:Integer (one round's score): Directly represents the number of points you get...

题目Given an array with n integers, your task is to check if it could become non-decreasing by modifying at most 1 element.We define an array is non-decreasing if array[i] <= array[i + 1] holds f...

题目In a given integer array nums, there is always exactly one largest element.Find whether the largest element in the array is at least twice as much as every other number in the array.If it is, ...

题目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 index is equal...

题目Given a binary array, find the maximum number of consecutive 1s in this array.Example 1:Input: [1,1,0,1,1,1]Output: 3Explanation: The first two digits or the last three digits are consecut

题目Suppose you have a long flowerbed in which some of the plots are planted and some are not. However, flowers cannot be planted in adjacent plots - they would compete for water and both would die.

题目Rotate an array of n elements to the right by k steps.For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].Note: Try to come up as many solutions as you ...

题目Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most...

题目Given an array of integers and an integer k, you need to find the number of unique k-diff pairs in the array. Here a k-diff pair is defined as an integer pair (i, j), where i and j are both number...

题目In MATLAB, there is a very useful function called ‘reshape’, which can reshape a matrix into a new one with different size but keep its original data.You’re given a matrix represented by a two-d...

题目Given an integer array, you need to find one continuous subarray that if you only sort this subarray in ascending order, then the whole array will be sorted in ascending order, too.You need to f...

题目Given an integer array, find three numbers whose product is maximum and output the maximum product.Example 1:Input: [1,2,3]Output: 6Example 2:Input: [1,2,3,4]Output: 24Note:1.The l...

题目Given an array consisting of n integers, find the contiguous subarray of given length k that has the maximum average value. And you need to output the maximum average value.Example 1:Input: [1...

题目Given an unsorted array of integers, find the length of longest continuous increasing subsequence (subarray).Example 1:Input: [1,3,5,4,7]Output: 3Explanation: The longest continuous increasi...

题目Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the two numbers s

题目Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every elemen

题目Given an array nums, write a function to move all 0’s to the end of it while maintaining the relative order of the non-zero elements.For example, given nums = [0, 1, 0, 3, 12], after calling you

题目Given an array of integers where 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.Find all the elements of [1, n] inclusive that do not appear in this array.

题目A matrix is Toeplitz if every diagonal from top-left to bottom-right has the same element.Now given an M x N matrix, return True if and only if the matrix is Toeplitz.Example 1:Input: matrix

题目Given a non-empty array of integers, return the third maximum number in this array. If it does not exist, return the maximum number. The time complexity must be in O(n).Example 1:Input: [3, 2,