Problem Suppose a sorted array 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 found in the array return its index, otherwise return -1. You may assume no duplicate exists in the array. Follow up: what if duplicates are allowed? ...
Problem Write a function that takes a string as input and returns the string reversed. Examples Example 1: Given s = "hello", return "olleh". Given s = “kodeknight” , return “thginkedok“. Solution Method 0 - Iterative, Not in Place In Java, string is immutable. So, cannot do in place!. public String reverseString(String s) { int n = s.length; char[] reversed = s.toCharArray(); return reverse(reversed); } ...
Problem Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order of the elements should be kept the same. Then return the number of unique elements in nums. Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory. Note that even though we want you to return the new length, make sure to change the original array as well in place. ...
Problem Given an integer array nums and an integer val, remove all occurrences of val in nums in-place. The relative order of the elements may be changed. Since it is impossible to change the length of the array in some languages, you must instead have the result be placed in the first part of the array nums. More formally, if there are k elements after removing the duplicates, then the first k elements of nums should hold the final result. It does not matter what you leave beyond the first k elements. ...
Problem Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order. OR Given a collection of numbers, return all possible permutations. Examples Example 1: nums = [1,2,3] Output: [ [1,2,3] [1,3,2] [2,1,3] [2,3,1] [3,1,2] [3,2,1] ] ...
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 contains a single digit. Add the two numbers and return the sum as a linked list. You may assume the two numbers do not contain any leading zero, except the number 0 itself. Examples Example 1: (2 -> 4 -> 3) + (5 -> 6 -> 4) => 7 -> 0 -> 8 Input: l1 = [2,4,3], l2 = [5,6,4] Output: [7,0,8] Explanation: 342 + 465 = 807 ...
Problem We are playing the Guess Game. The game is as follows: I pick a number from 1 to n. You have to guess which number I picked. Every time you guess wrong, I will tell you whether the number I picked is higher or lower than your guess. You call a pre-defined API int guess(int num), which returns three possible results: -1: Your guess is higher than the number I picked (i.e. num > pick). 1: Your guess is lower than the number I picked (i.e. num < pick). 0: your guess is equal to the number I picked (i.e. num == pick). Return the number that I picked. ...
Problem Given an array nums of n integers where nums[i] is in the range [1, n], return an array of all the integers in the range [1, n] that do not appear in nums. Examples Example 1: Input: nums = [4,3,2,7,8,2,3,1] Output: [5,6] Example 2: Input: nums = [1,1] Output: [2] ...
Problem Given an array of integers nums, calculate the pivot index of this array. The pivot index is the index where the sum of all the numbers strictly to the left of the index is equal to the sum of all the numbers strictly to the index’s right. If the index is on the left edge of the array, then the left sum is 0 because there are no elements to the left. This also applies to the right edge of the array. ...
Problem Given the root of a binary tree and an integer targetSum, return true if the tree has a root-to-leaf path such that adding up all the values along the path equals targetSum. A leaf is a node with no children. Examples Example 1: graph TD; A[5] --> B[4] & C[8] B --> D[11] & E[null] C --> F[13] & G[4] D --> H[7] & I[2] G --> L[5] & M[1] style A fill:#f9f style B fill:#f9f style D fill:#f9f style I fill:#f9f ...