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Leetcode[day22] - Bitwise AND of Numbers Range
Given a range [m, n] where 0 > 1; shift++; } return n
May LeetCoding Challenge[Day5] - First Unique Character in a String
Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1. Note: You may assume the string contain only lowercase letters. s = "leetcode" return 0. s = "loveleetcode" return 2. 1. 알고리즘을 해결하기 위해서 생각한 방법 - 해당 문제는 문자열이 입력으로 주어질 때, 특정 인덱스의 문자가 중복되지 않는 문자인 지 확인하는 문제이다. - 문자를 카운팅하고, 해당 문자열이 몇 개 존재하는 지 확인해야 한다. - 문자열을 카운팅하기 가장 쉬운 자료구조인 Map을 사용했고,..
May LeetCoding Challenge[Day4] - Number Complement
Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation. Input: 5 Output: 2 Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. 1. 알고리즘을 해결하기 위해서 생각한 방법 - 우선, 해당 문제는 5라는 값이 주어졌을 때, 이진 값으로 101이 되는데, 이 때 해당 값의 반대 되는 값을 return하면 된다. - 여기서, 해당 값의 반대 되는 값의 단어적 정의는 잘 모르겠고, complem..
May LeetCoding Challenge[Day3] - Ransom Note
Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note can be constructed from the magazines ; otherwise, it will return false. Each letter in the magazine string can only be used once in your ransom note. Note:You may assume that both strings contain only lowercase letters. canConstruct("a", "..
May LeetCoding Challenge[Day2] - Jewels and Stones
You're given strings J representing the types of stones that are jewels, and S representing the stones you have. Each character in S is a type of stone you have. You want to know how many of the stones you have are also jewels. The letters in J are guaranteed distinct, and all characters in J and S are letters. Letters are case sensitive, so "a" is considered a different type of stone from "A". ..
May LeetCoding Challenge[Day1] - 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 find out the first bad one, which causes all the following ones to be..
Leetcode[day20] - Construct Binary Search Tree from Preorder Traversal
Return the root node of a binary search tree that matches the given preorder traversal. (Recall that a binary search tree is a binary tree where for every node, any descendant of node.left has a value node.val. Also recall that a preorder traversal displays the value of the node first, then traverses node.left, then traverses node.right.) It's guaranteed that for the given test cases there is al..
Leetcode[day19] -Search in Rotated Sorted Array
Suppose an array sorted in ascending order 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. Your algorithm's runtime complexity must be in the order of O(log n). Input: nums = [4,5,6,7,0,1,2]..