내 맘대로 알고리즘
May LeetCoding Challenge[Day16] - Odd Even Linked List
Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes. You should try to do it in place. The program should run in O(1) space complexity and O(nodes) time complexity. The relative order inside both the even and odd groups should remain as it was in the input. The first node is cons..
May LeetCoding Challenge[Day15] - Maximum Sum Circular Subarray
Given a circular array C of integers represented by A, find the maximum possible sum of a non-empty subarray of C. Here, a circular array means the end of the array connects to the beginning of the array. (Formally, C[i] = A[i] when 0 = 0.) Also, a subarray may only include each element of the fixed buffer A at most once. (Formally, for a subarray C[i], C[i+1], ..., C[j], there does not exist i
May LeetCoding Challenge[Day14] - Implement Trie (Prefix Tree)
Implement a trie with insert, search, and startsWith methods. Note: You may assume that all inputs are consist of lowercase letters a-z.All inputs are guaranteed to be non-empty strings. Trie trie = new Trie(); trie.insert("apple"); trie.search("apple"); // returns true trie.search("app"); // returns false trie.startsWith("app"); // returns true trie.insert("app"); trie.search("app"); // returns..
May LeetCoding Challenge[Day13] - Remove K Digits
Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible. Note: - The length of num is less than 10002 and will be ≥ k. - The given num does not contain any leading zero. Input: num = "1432219", k = 3 Output: "1219" Explanation: Remove the three digits 4, 3, and 2 to form the new number 1219 which is the smallest. 1..
May LeetCoding Challenge[Day12] - Single Element in a Sorted Array
You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once. Find this single element that appears only once. Input: [3,3,7,7,10,11,11] Output: 10 1. 알고리즘을 해결하기 위해서 생각한 방법 - 쉬어가는 날인가보다. - 배열이 주어질 때, 배열 중에서 혼자 짝이 되지 않는 숫자를 찾는 문제이다. - 2020/04/20 - [내 맘대로 알고리즘] - LeetCode[day1] - Single Number - 4월에 첫 번째, Sing..
May LeetCoding Challenge[Day11] - Flood Fill
An image is represented by a 2-D array of integers, each integer representing the pixel value of the image (from 0 to 65535). Given a coordinate (sr, sc) representing the starting pixel (row and column) of the flood fill, and a pixel value newColor, "flood fill" the image. To perform a "flood fill", consider the starting pixel, plus any pixels connected 4-directionally to the starting pixel of t..
May LeetCoding Challenge[Day10] - Find the Town Judge
In a town, there are N people labelled from 1 to N. There is a rumor that one of these people is secretly the town judge. If the town judge exists, then: 1. The town judge trusts nobody. 2. Everybody (except for the town judge) trusts the town judge. 3. There is exactly one person that satisfies properties 1 and 2. You are given trust, an array of pairs trust[i] = [a, b] representing that the pe..
May LeetCoding Challenge[Day9] - Valid Perfect Square
Given a positive integer num, write a function which returns True if num is a perfect square else False. Note: Do not use any built-in library function such as sqrt. Input: 16 Output: true 1. 알고리즘을 해결하기 위해서 생각한 방법 - 해당 문제는 input 숫자가 n*n 인 숫자인가에 관련된 문제이다. - 특정 숫자를 고르는 것이기 때문에, 이진탐색을 생각했다. - 특정 숫자를 고르는 문제와 같이, 이진탐색을 하는 조건을 알게 되었다. - 1~N까지 범위가 주어졌을 때, 숫자 하나를 선택할 때 가장 빠르게 찾기 위해서는 가장 적합하다고 생각하게 되었다. ..