Company/Google

Problem Given a sorted linked list, delete all duplicates such that each element appear only once. Examples Example 1: Given 1->1->2, return 1->2. Input: head = [1,1,2] Output: [1,2] ...

Problem Reverse a linked list. Follow up 1 - Do it in-place and in one-pass. Follow up 2 - Can you do it with only 2 pointers. Examples For example: Input: 1->2->3->4->5->NULL Output: 5->4->3->2->1->NULL ...

Problem Given a linked list, remove the nth node from the end of list and return its head. Examples Example 1: Input: head = [1,2,3,4,5], n = 2 Output: [1,2,3,5] Explanation: Given linked list 1->2->3->4->5 and n = 2, the result is 1->2->3->5. ...

Problem Given an input string s and a pattern p, implement regular expression matching with support for '.' and '*' where: '.' Matches any single character. '*' Matches zero or more of the preceding element. The matching should cover the entire input string (not partial). Examples Some examples: isMatch("aa","a") ? false isMatch("aa","a.") ? true isMatch("aaa","ab*") ? false isMatch("aa", ".*") ? true isMatch("aa", "a*") ? true isMatch("ab", ".*") ? true isMatch("aabaa", "a*b.*") ? false ...

Problem You have a long flowerbed in which some of the plots are planted, and some are not. However, flowers cannot be planted in adjacent plots. Given an integer array flowerbed containing 0’s and 1’s, where 0 means empty and 1 means not empty, and an integer n, return if n new flowers can be planted in the flowerbed without violating the no-adjacent-flowers rule. Examples Example 1: ...

Problem You are given an integer array cost where cost[i] is the cost of ith step on a staircase. Once you pay the cost, you can either climb one or two steps. You can either start from the step with index 0, or the step with index 1. Return the minimum cost to reach the top of the floor. Examples Example 1: Input: cost = [10,15,20] Output: 15 Explanation: You will start at index 1. - Pay 15 and climb two steps to reach the top. The total cost is 15. ...

Problem 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. You must write an algorithm with O(log n) runtime complexity. Examples Example 1: Input: nums = [1,3,5,6], target = 5 Output: 2 ...

Problem Remove all elements from a linked list of integers that have value val. Example Example 1: Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6 Return: 1 --> 2 --> 3 --> 4 --> 5 ...

Problem Given the head of a singly linked list, return true if it is a palindrome or false otherwise. Examples Example 1: Input: head = [1,2,2,1] Output: true head = 1 -> 2 -> 2 -> 1 Example 2: Input: head = [1,2] Output: true head = 1 -> 2 ...

Problem There are several cards arranged in a row, and each card has an associated number of points. The points are given in the integer array cardPoints. In one step, you can take one card from the beginning or from the end of the row. You have to take exactly k cards. Your score is the sum of the points of the cards you have taken. Given the integer array cardPoints and the integer k, return the maximum score you can obtain. ...