qz530308783的专栏

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 poss...

Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array.Formally the function should:Return true if there exists i, j, k such that arr[i] ar

Given a positive integer n and you can do operations as follow:If n is even, replace n with n/2.If n is odd, you can replace n with either n + 1 or n - 1.What is the minimum number o

Given a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters.This is case sensitive, for example "Aa" is not con

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 3.两个数相加但是不能用+、-运算符则考虑从位运算的角度来解决问题，观察二进制加法的特点，如果没有进位的时候结果是

Find the sum of all left leaves in a given binary tree.Example: 3 / \ 9 20 / \ 15 7There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24

Given two strings s and t which consist of only lowercase letters.String t is generated by random shuffling string s and then add one more letter at a random position.Find the letter that was

Given n, how many structurally unique BST's (binary search trees) that store values 1...n?For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \

Given a string s and a string t, check if s is subsequence of t.You may assume that there is only lower case English letters in both s and t. t is potentially a very long (length ~= 500,000) strin

A binary watch has 4 LEDs on the top which represent the hours (0-11), and the 6 LEDs on the bottom represent the minutes (0-59).Each LED represents a zero or one, with the least significant bit o

You are given an integer array nums and you have to return a new counts array. The counts array has the property where counts[i] is the number of smaller elements to the right of nums[i].Example

Write a program to find the n-th ugly number.Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 1, 2, 3, 4, 5, 6, 8, 9, 10, 12 is the sequence of the first 

Given a binary tree, find the maximum path sum.For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The

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 tota

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 / \

Given an array of integers A and let n to be its length.Assume Bk to be an array obtained by rotating the array A k positions clock-wise, we define a "rotation function" F on A as follow:

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 c

Count the number of segments in a string, where a segment is defined to be a contiguous sequence of non-space characters.Please note that the string does not contain any non-printable characters.

A sequence of number is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the same.For example, these are arithmetic sequenc

Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.Example 1:Input: "Let's take LeetCode contes

Given scores of N athletes, find their relative ranks and the people with the top three highest scores, who will be awarded medals: "Gold Medal", "Silver Medal" and "Bronze Medal".Example 1:In

Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there are less than k characters left, reverse all of th

Given an integer, return its base 7 string representation.Example 1:Input: 100Output: "202"Example 2:Input: -7Output: "-10"Note: The input will be in range of [-1e7, 1e

Total Accepted: 14611Total Submissions: 29825Difficulty: EasyContributors:love_FawnFor a web developer, it is very important to know how to design a web page's size. So, given a specific recta

Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.Example:Input: 1 \ 3 / 2Output:1Explanation:Th

Given a word, you need to judge whether the usage of capitals in it is right or not.We define the usage of capitals in a word to be right when one of the following cases holds:All letters in t

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 consecutiv

Given a List of words, return the words that can be typed using letters of alphabet on only one row's of American keyboard like the image below.Example 1:Input: ["Hello", "Alaska", "Da

Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length at that position.Determine i

The Hamming distance between two integers is the number of positions at which the corresponding bits are different.Given two integers x and y, calculate the Hamming distance.Note:0 ≤ x, 

You are given a map in form of a two-dimensional integer grid where 1 represents land and 0 represents water. Grid cells are connected horizontally/vertically (not diagonally). The grid is completely

Write a program that outputs the string representation of numbers from 1 to n.But for multiples of three it should output “Fizz” instead of the number and for the multiples of five output “Buzz”.

其实整体思想和归并k个有序数组是一样的，有三种方法，效率最慢的是两个有序链表和并之后再与其他链表合并，需要合并n-1次。第二种方法是两两一组分别归并，第三种方法是采用一个k大小的堆，刚开始的时候将每个链表的第一个元素都放入k的最小堆中，那么就可以直接得到k中最小的值,再将k中刚取出的最小值的下一个节点加入堆中，直到所有的元素都处理完成。/** * Definition for singly-

Given a sorted linked list, delete all duplicates such that each element appear only once.For example,Given 1->1->2, return 1->2.Given 1->1->2->3->3, return 1->2->3.class Solution {public

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 t

Given a string containing only digits, restore it by returning all possible valid IP address combinations.For example:Given "25525511135",return ["255.255.11.135", "255.255.111.35"]. (Order

There are two sorted arrays nums1 and nums2 of size m and n respectively.Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).Example 1:nums1 =

Given a linked list, return the node where the cycle begins. If there is no cycle, return null.Note: Do not modify the linked list.Follow up:Can you solve it without using extra space?

Given a n x n matrix where each of the rows and columns are sorted in ascending order, find the kth smallest element in the matrix.Note that it is the kth smallest element in the sorted order, not

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.题目要找第一个没有重复的字