题目一: 给定一个文本文件 file.txt,请只打印这个文件中的第十行. 示例: 假设 file.txt 有如下内容: Line 1 Line 2 Line 3 Line 4 Line 5 Line 6 Line 7 Line 8 Line 9 Line 10 你的脚本应当显示第十行: Line 10 说明: 如果文件少于十行,你应当输出什么? 至少有三种不同的解法,请尝试尽可能多的方法来解题. # Read from the file file.txt and output the tent…
Range Sum Query - Mutable Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. The update(i, val) function modifies nums by updating the element at index i to val. Example: Given nums = [1, 3, 5] sumRa…
Additive Number Additive number is a string whose digits can form additive sequence. A valid additive sequence should contain at least three numbers. Except for the first two numbers, each subsequent number in the sequence must be the sum of the prec…
Range Sum Query 2D - Immutable Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2). The above rectangle (with the red border) is defined by (row…
Longest Increasing Subsequence Given an unsorted array of integers, find the length of longest increasing subsequence. Example: Input: [10,9,2,5,3,7,101,18] Output: 4 Explanation: The longest increasing subsequence is [2,3,7,101], therefore the lengt…
Game of Life According to the Wikipedia's article: "The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970." Given a board with m by n cells, each cell has an initial…
Ugly Number II Write a program to find the n-th ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. Example: Input: n = 10 Output: 12 Explanation: 1, 2, 3, 4, 5, 6, 8, 9, 10, 12 is the sequence of the first 10 ugl…
H-Index II Given an array of citations sorted in ascending order (each citation is a non-negative integer) of a researcher, write a function to compute the researcher's h-index. According to the definition of h-index on Wikipedia: "A scientist has in…
Search a 2D Matrix II Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties: Integers in each row are sorted in ascending from left to right. Integers in each column are sorted in ascendin…
Sliding Window Maximum Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window moves right by one position.…
Product of Array Except Self Given an array nums of n integers where n > 1, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i]. Example: Input: [1,2,3,4] Output: [24,12,8,6] Constraint: It's…
Lowest Common Ancestor of a Binary Tree Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree. According to the definition of LCA on Wikipedia: "The lowest common ancestor is defined between two nodes p and q as th…
Kth Smallest Element in a BST Given a binary search tree, write a function kthSmallest to find the kth smallest element in it. Example 1: Input: root = [3,1,4,null,2], k = 1 3 / \ 1 4 \ 2 Output: 1 Example 2: Input: root = [5,3,6,2,4,null,null,1], k…
Majority Element II Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times. Note: The algorithm should run in linear time and in O(1) space. Example 1: Input: [3,2,3] Output: [3] Example 2: Input: [1,1,1,3,3,2,2,2] Ou…
Summary Ranges Given a sorted integer array without duplicates, return the summary of its ranges. Example 1: Input: [0,1,2,4,5,7] Output: ["0->2","4->5","7"] Explanation: 0,1,2 form a continuous range; 4,5 form a contin…
Basic Calculator Implement a basic calculator to evaluate a simple expression string. The expression string may contain open ( and closing parentheses ), the plus + or minus sign -, non-negative integers and empty spaces ``. Example 1: Input: "1 + 1&…
Rectangle Area Find the total area covered by two rectilinear rectangles in a 2D plane. Each rectangle is defined by its bottom left corner and top right corner as shown in the figure. Example: Input: A = -3, B = 0, C = 3, D = 4, E = 0, F = -1, G = 9…
Count Complete Tree Nodes Given a complete binary tree, count the number of nodes. Note: Definition of a complete binary tree from Wikipedia: In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the…
Combination Sum III Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Note: All numbers will be positive integers. The soluti…
Kth Largest Element in an Array Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element. Example 1: Input: [3,2,1,5,6,4] and k = 2 Output: 5 Example 2: Input: [3,2,3…
House Robber II You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Mean…
Add and Search Word - Data structure design Design a data structure that supports the following two operations: void addWord(word) bool search(word) search(word) can search a literal word or a regular expression string containing only letters a-z or…
Course Schedule II There are a total of n courses you have to take, labeled from 0 to n-1. Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1] Given the total number o…
Minimum Size Subarray Sum Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous subarray of which the sum ≥ s. If there isn't one, return 0 instead. Example: Input: s = 7, nums = [2,3,1,2,4,3] Output:…
Count Primes Count the number of prime numbers less than a non-negative number, *n*. Example: Input: 10 Output: 4 Explanation: There are 4 prime numbers less than 10, they are 2, 3, 5, 7. 解法1 埃氏筛法 class Solution { public: int countPrimes(int n) { if(…
Isomorphic Strings Given two strings *s* and *t*, determine if they are isomorphic. Two strings are isomorphic if the characters in *s* can be replaced to get *t*. All occurrences of a character must be replaced with another character while preservin…
