Sliding window algorithm is easy
Sliding window technique is used to reduce the use of nested loops and replace it with a single loop, thereby reducing the time complexity. Hand written notes
Tag: leetcode
704. Binary Search
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 = 9 Output: 4 Explanation: 9 exists in nums and its index is 4 Example…
35. Search Insert Position
Given a sorted array of distinct integers 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 must write an algorithm with O(log n) runtime complexity. Example 1: Input: nums = [1,3,5,6], target = 5 Output: 2 Example 2: Input:…
278. First Bad Version
You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each version is developed based on the previous version, all the versions after a bad version are also bad. Suppose you have n versions [1, 2, …, n] and you want to…
217. Contains Duplicate
Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct. Example 1: Input: nums = [1,2,3,1] Output: true Example 2: Input: nums = [1,2,3,4] Output: false Example 3: Input: nums = [1,1,1,3,3,4,3,2,4,2] Output: true Solution:
#34 Find First and Last Position of Element in Sorted Array
Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value. If target is not found in the array, return [-1, -1]. You must write an algorithm with O(log n) runtime complexity. Example 1: Input: nums = [5,7,7,8,8,10], target = 8 Output: [3,4] Example 2: Input: nums = [5,7,7,8,8,10], target = 6 Output: [-1,-1] Example…
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#796 Rotate String
Given two strings s and goal, return true if and only if s can become goal after some number of shifts on s. A shift on s consists of moving the leftmost character of s to the rightmost position. For example, if s = “abcde”, then it will be “bcdea” after one shift. Example 1: Input: s = “abcde”, goal = “cdeab” Output: true Example 2: Input: s = “abcde”, goal = “abced” Output: false Solution…
#316 Remove Duplicate Letters
Given a string s, remove duplicate letters so that every letter appears once and only once. You must make sure your result is the smallest in lexicographical order among all possible results. Example 1: Input: s = “bcabc” Output: “abc” Example 2: Input: s = “cbacdcbc” Output: “acdb” Solution : string removeDuplicateLetters(string s) {map umap;map umap1;string result =…
#125 Valid Palindrome
A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers. Given a string s, return true if it is a palindrome, or false otherwise. Example 1: Input: s = “A man, a plan, a canal: Panama” Output: true Explanation: “amanaplanacanalpanama” is…
#344 Reverse String
Write a function that reverses a string. The input string is given as an array of characters s. You must do this by modifying the input array in-place with O(1) extra memory. Example 1: Input: s = [“h”,”e”,”l”,”l”,”o”] Output: [“o”,”l”,”l”,”e”,”h”] Example 2: Input: s = [“H”,”a”,”n”,”n”,”a”,”h”] Output: [“h”,”a”,”n”,”n”,”a”,”H”] Constraints: 1 <= s.length <= 105 s[i] is a printable ascii character. Solution :…