99클럽 코테 스터디 33일차 TIL + 오늘의 학습 키워드

☑️ 문제: 리코쳇 로봇

https://school.programmers.co.kr/learn/courses/30/lessons/169199

프로그래머스

 

☑️ Code

import java.util.*;

class Solution {
    public int solution(String[] board) {
        int rowLen = board.length;
        int colLen = board[0].length();
        
        // 1. search start Index
        int startRow = 0, startCol = 0;
        for (int i = 0; i < rowLen; i++) {
            for (int j = 0; j < colLen; j++) {
                if (board[i].charAt(j) == 'R') {
                    startRow = i;
                    startCol = j;
                }
            }
        }

        // 2. start에서 시작하기
        int answer = bfs(board, startRow, startCol, rowLen, colLen);
        return answer;
    }
    
    public int bfs(String[] board, int row, int col, int rowLen, int colLen) {
        int[] dr = { 0, 0, -1, 1 };
        int[] dc = { -1, 1, 0, 0 };
        int[][] dist = new int[rowLen][colLen];
        for (int i = 0; i < rowLen; i++) {
            for (int j = 0; j < colLen; j++) {
                dist[i][j] = rowLen * colLen + 1;
            }
        }
        Queue<Integer> queueR = new LinkedList<>();
        Queue<Integer> queueC = new LinkedList<>();

        dist[row][col] = 0;
        queueR.offer(row);
        queueC.offer(col);
        
        while (!queueR.isEmpty()) {
            row = queueR.poll();
            col = queueC.poll();
            if (board[row].charAt(col) == 'G') {
                return dist[row][col];
            }
            
            for (int i = 0; i < 4; i++) {
                int nRow = row;
                int nCol = col;
                
                while(isBound(nRow, nCol, rowLen, colLen) && board[nRow].charAt(nCol) != 'D') {
                    nRow += dr[i];
                    nCol += dc[i];                    
                }
                
                nRow -= dr[i];
                nCol -= dc[i];                    
                if (dist[nRow][nCol] > dist[row][col] + 1) {
                    dist[nRow][nCol] = dist[row][col] + 1;
                    queueR.offer(nRow);
                    queueC.offer(nCol);
                }
            }
        }        
        return -1;
    }
    
    boolean isBound(int r, int c, int rLen, int cLen) { 
        return r >= 0 && c >= 0 && r < rLen && c < cLen;
    }
}