silvergoni.builder()

https://leetcode.com/problems/number-of-provinces/ 1. 2022/04/10 시도 소요시간: 38분 class Solution { private int[] rootArray; private int[] rank; public int findCircleNum(int[][] isConnected) { rootArray = new int[isConnected.length]; rank = new int[isConnected.length]; //init for (int i=0; i

Leetcode 문제를 풀어가면서 느끼고 문제를 풀기전에 먼저 생각해봤으면 좋았을 내용을 하나씩 더해간다. 물론 없어지기도 하고 관련 있는 내용은 합치기도 한다. 알고리즘을 풀면서 기억하기 divide and conquer(quick sort, merge sort) 원리 이해하기 https://silvergoni.tistory.com/entry/leetcode-347-Top-K-Frequent-Element https://silvergoni.tistory.com/entry/leetcode-148-Sort-List Heap, PriorityQueue while문에서 pq.size()를 꼭 확인하자. https://silvergoni.tistory.com/entry/programmersH-Index 우선순위..

https://leetcode.com/problems/top-k-frequent-elements/ 2. 2022.04.08 시도 소요시간: 7분 class Solution { public int[] topKFrequent(int[] nums, int k) { Map countMap = new HashMap(); for (int i=0; i { return o1.getValue().compareTo(o2.getValue()) * -1; }); int counter=0; int[] ret = new int[k]; for (Map.Entry each: list) { ret[counter++] = each.getKey(); if (counter == k) { break; } } return ret; } } 풀이..

https://programmers.co.kr/learn/courses/30/lessons/42579 1. 2022.04.07 시도 소요시간: 44분 import java.util.*; import java.util.Map.Entry; class Solution { public int[] solution(String[] genres, int[] plays) { Map songMap = new HashMap(); Map genreMap = new HashMap(); for(int i=0; i { int ret = o1.getValue().compareTo(o2.getValue()) * -1; if (ret == 0) { return o1.getKey().compareTo(o2.getKey()); } ret..

https://leetcode.com/problems/unique-email-addresses/ 1. 2022.04.01 시도 소요시간: 10분(4분 문제 읽기, 6분 코딩) class Solution { public int numUniqueEmails(String[] emails) { Set ret = new HashSet(); for (String email: emails) { String rawLocalName = email.split("@")[0]; String domainName = email.split("@")[1]; String removeAfterPlus = rawLocalName.split("\\+")[0]; String removeDots = removeAfterPlus.replace(..

https://leetcode.com/problems/spiral-matrix-iii/ 1. 2022.03.31 시도 소요시간: 21분 class Solution { private String[] d = new String[]{"RIGHT", "DOWN", "LEFT", "UP"}; public int[][] spiralMatrixIII(int rows, int cols, int rStart, int cStart) { int rowSize = 1; int colSize = 1; int p=rStart; int q=cStart; int[][] ret = new int[rows*cols][2]; int directionIndex = 0; int counter = 0; ret[counter++] = new i..

https://leetcode.com/problems/spiral-matrix-ii/ 1. 2022.03.31 시도 소요시간: 5분 class Solution { private String[] d = new String[]{"RIGHT", "DOWN", "LEFT", "UP"}; public int[][] generateMatrix(int n) { int rowSize = n; int colSize = n; int p = 0; int q = -1; int[][] matrix = new int[n][n]; int directionIndex = 0; int number = 1; while( rowSize != 0 || colSize != 0) { String direction = d[directionInde..

https://leetcode.com/problems/spiral-matrix/ 1. 2022.03.31 시도 소요시간: 11분 class Solution { private String[] d = new String[]{"RIGHT", "DOWN", "LEFT", "UP"}; public List spiralOrder(int[][] matrix) { int rowSize = matrix.length; int colSize = matrix[0].length; int p = 0; int q = -1; List ret = new ArrayList(); int directionIndex = 0; while ( rowSize !=0 && colSize != 0) { String direction = d[direc..

https://leetcode.com/problems/reverse-only-letters/ 1. 2022.03.30 시도 소요시간: 9분 class Solution { public String reverseOnlyLetters(String s) { int left = 0; int right = s.length() -1; String ls =""; String rs =""; while(left < right) { char lc = s.charAt(left); char rc = s.charAt(right); if (isEnglishLetter(lc) == false) { left++; ls = ls + lc; continue; } else if (isEnglishLetter(rc) == false) { r..

https://leetcode.com/problems/sum-of-left-leaves/ 1. 2022.03.30 시도 소요시간: 12분(iterative), 5분(recursive) // iterative class Solution { public int sumOfLeftLeaves(TreeNode root) { if (root == null) { return 0; } int sum = 0; if (root.left != null) { int left = sumOfLeftLeaves(root.left); if (root.left.left == null && root.left.right == null) { sum = left + root.left.val; } else { sum += left; } } i..