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Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value.Your algorithm’s runtime complexity must be in the order of O(log n).If the t...

Leetcode 41. First Missing PositivePython 解题思路class Solution: def firstMissingPositive(self, nums): nums.sort() res = 1 for num in nums: if num == res: ...

Leetcode 40. Combination Sum IIPython 解题思路class Solution: def __init__(self): self.res = [] self.path = [] self.candidates = [] def dfs(self, target, ind): i...

Leetcode 43. Multiply StringsPython 解题思路class Solution: def multiply(self, num1, num2): num1, num2 = int(num1), int(num2) ret = return str(num1 * num2)solu = Solution()...

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 possible or...

You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once and wi...

Given a linked list, swap every two adjacent nodes and return its head.You may not modify the values in the list’s nodes, only nodes itself may be changed.Example:Given 1->2->3->4, you sho...

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 the number of n...

Given a sorted array nums, 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 by modifyin...

Given an array nums and a value val, 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 by modifying the input array...

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.Example 1:Input: haystack = “hello”, needle = “ll”Output: 2Example 2:Input: haystack = “aaa...

Given two integers dividend and divisor, divide two integers without using multiplication, division and mod operator.Return the quotient after dividing dividend by divisor.The integer division shoul...

iven a set of candidate numbers (candidates) (without duplicates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.The same repeated...

Write a program to solve a Sudoku puzzle by filling the empty cells.A sudoku solution must satisfy all of the following rules:Each of the digits 1-9 must occur exactly once in each row.Each of the ...

Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:Each row must contain the digits 1-9 without repetition.Each column must contain...

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.You may assume no duplicates in the array.Ex...

Leetcode 42. Trapping Rain WaterPython 解题思路class Solution(object): def trap(self, height): res = 0 mx = 0 n = len(height) dp = [] for i in range(n): ...