stlst的专栏

Problem Given a text file file.txt that contains list of phone numbers (one per line), write a one liner bash script to print all valid phone numbers.You may assume that a valid phone number must appe

Problem：思路： 题目只要求讨论1-3999，所以直接穷举各种情况吧，从千位，百位，十位到个位。Solution：# -*- coding: utf-8 -*-"""Created on Thu Jan 26 11:36:04 2017@author: liangsht"""class Solution(object): def intToRoman(self, num):

Problem: Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999.思路： 方法与LeetCode 12题同理。Solution：class Solution(object): def romanToInt(self

Problem: 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: [ “((()))”, “(()()

Problem: 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 another array, you must do this in

Problem: Write a function to find the longest common prefix string amongst an array of strings.思路: 1. 纵向遍历法。遍历字符串list strs中，每个str的相同index。如果相同则继续，如果不同则跳出循环。遍历完了strs中i个str之后，index自增1，继续重新遍历。时间复杂度O(n

Problem: Given a linked list, remove the nth node from the end of list and return its head. For example, Given linked list: 1->2->3->4->5, and n = 2. After removing the second

Problem: Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.Idea: Use two points to go through these two string individu

Problem: 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 constant m

Problem Given n non-negative integers a1, a2, …, an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Fi

Problem How would you print just the 10th line of a file?For example, assume that file.txt has the following content: Line 1 Line 2 Line 3 Line 4 Line 5 Line 6 Line 7 Line 8

ProblemWrite a bash script to calculate the frequency of each word in a text file words.txt.For simplicity sake, you may assume:words.txt contains only lowercase characters and space ’ ’ characters.E

Problem Given a text file file.txt, transpose its content.You may assume that each row has the same number of columns and each field is separated by the ’ ’ character.For example, if file.txt has the

ProblemGiven a collection of distinct numbers, return all possible permutations.For example, [1,2,3] have the following permutations: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1],

Problem: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 ...

Problem: Given a string containing just the characters ‘(’ and ‘)’, find the length of the longest valid (well-formed) parentheses substring.For “(()”, the longest valid parentheses substring is “(...

Problem Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).You are given a target value to search. If f...

Problem: 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 numbers an

Problem: 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 would ha

Problem: Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.Idea:General solution (the same as Merge 2 Sorted Lists Question) Use k index to record

Problem: 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 should use only const

Problem: Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. The brackets must close in the correct order, "()" and "()[]{}" ar

Problem: Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.Idea: Basic singly-linked list operation. Use t

Problem: 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 buttons) is given below.

Problem: 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: Th

[Leetcode] 1. Two SumProblem Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution

Problem: 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

Problem： Given a string, find the length of the longest substring without repeating characters. Examples: Given “abcabcbb”, the answer is “abc”, which the length is 3. Given “bbbbb”, the a

Problem: Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. k is a positive integer and is less than or equal to the length of the linked list. If th

Problem: 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” Note: “aba” is al

Problem： The string “PAYPALISHIRING” is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility) P A H

Problem： Reverse digits of an integer. Example1: x = 123, return 321 Example2: x = -123, return -321 click to show spoilers. Have you thought about this? Here are some good questions t

Problem： Implement atoi to convert a string to an integer. Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possi

Problem: Determine whether an integer is a palindrome. Do this without extra space. Some hints: Could negative integers be palindromes? (ie, -1) If you are thinking of converting the int