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Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.You must write an algorithm with O(log n) runtime complexity. Example 1:Input: nums = [-1,0,3,5,9,12], target = 9Output: 4Explanation: 9 exists in nums and its index is 4Example 2:Input: nums = [-1,0,3,..

Given an array of points where points[i] = [xi, yi] represents a point on the X-Y plane and an integer k, return the k closest points to the origin (0, 0).The distance between two points on the X-Y plane is the Euclidean distance (i.e., √(x1 - x2)2 + (y1 - y2)2).You may return the answer in any order. The answer is guaranteed to be unique (except for the order that it is in). Example 1:Input: po..

Given an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands.An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water. Example 1:Input: grid = [ ["1","1","1","1","0"], ["1","1","0","1","0"], ["1","1","0","0","0"], ["0"..

Given the head of a singly linked list, return true if it is a palindrome or false otherwise. Example 1:Input: head = [1,2,2,1]Output: trueExample 2:Input: head = [1,2]Output: false Constraints:The number of nodes in the list is in the range [1, 105].0  Follow up: Could you do it in O(n) time and O(1) space?  code by python:# Definition for singly-linked list.# class ListNode:# def __init__(..

Given an integer array nums and an integer k, return the kth largest element in the array.Note that it is the kth largest element in the sorted order, not the kth distinct element.Can you solve it without sorting? Example 1:Input: nums = [3,2,1,5,6,4], k = 2Output: 5Example 2:Input: nums = [3,2,3,1,2,4,5,5,6], k = 4Output: 4 Constraints:1 -104  code by python:from collections import Counterclass..

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.An input string is valid if:Open brackets must be closed by the same type of brackets.Open brackets must be closed in the correct order.Every close bracket has a corresponding open bracket of the same type. Example 1:Input: s = "()"Output: trueExample 2:Input: s = "()[]{}"Outpu..