알고리즘 공식

js로 queue 구현

class MyQueue {
    constructor() {
        this.input = [];
        this.output = [];
        this.size = 0;
    }
    enque(val) {
        this.input.push(val);
        this.size++;
    }
    deque() {
        if(this.output.length === 0) {
            this.output = this.input.reverse();
            this.input = [];
        }
        this.size--;
        return this.output.pop();
    }
}

    const dr = [-1, 1, 0, 0];
    const dc = [0, 0, -1, 1];
    const R = maps.length;
    const C = maps[0].length;
    const visit = Array(R).fill(null).map(() => Array(C).fill(false));
    const que = new MyQueue();

플로이드 와샬

function solution (n, s, a, b, fares) {
  const board = new Array(n).fill().map(_ => new Array(n).fill(Infinity));
  
  for(let i = 0; i < n; i++) 
    board[i][i] = 0;
  
  fares.forEach(pos => {
    const [x, y, weight] = pos;
    board[x-1][y-1] = weight;
    board[y-1][x-1] = weight;
  });
  
	// k는 경유노드, i는 시작노드, j는 도착노드
  for(let k = 0; k < n; k++) {
    for(let i = 0; i < n; i++) {
      for(let j = 0; j < n; j++) {
        if(board[i][j] > board[i][k] + board[k][j])
          board[i][j] = board[i][k] + board[k][j];
      }
    }
  }
  
  let answer = board[s-1][a-1] + board[s-1][b-1];
  for(let i = 0; i < n; i++) {
    const shortest = board[s-1][i] + board[i][a-1] + board[i][b-1];
    answer = Math.min(answer, shortest);
  }
  
  return answer;
}

union find

function solution(n, computers) {
    const getParent = (arr, x) => {
        if(arr[x] === x) return x;
        return arr[x] = getParent(arr, arr[x]);
    }
    
    const unionParent = (arr, a, b) => {
        a = getParent(arr, a);
        b = getParent(arr, b);
        
        if(a < b) {
            arr[b] = a;
        }
        else if (a === b) {
            return;
        }
        else {
            arr[a] = b;
        }
    }
    
    let answer = 0;
    let parent = Array(n).fill(false);
    
    for(let i = 0; i < n; i++){
        parent[i] = i;
    }

    for(let i = 0; i < n; i++){
        for(let j = 0; j < n; j++){
            if(i === j){
                continue;
            }

            if(computers[i][j]){
                unionParent(parent, i, j);
            }
        }
    }
        
    for(let i = 0; i < n; i++){
        if(parent[i] === i){
            answer++;
        }
    }
    
    return answer;
}

배열의 특정 값 삭제

const food = ["pizza", "mango", "kimchi", "kimbab"];
const target = 1;

const answer = [...food.slice(0, target) , ...food.slice(target+1);