프로그래머스 / 리코쳇 로봇

 

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

주의할 점. 
목표도 통과해 버린다. 목표에 멈출 수 있어야 성공~! 

파이썬

def solution(board):
    que = []
    for x, row in enumerate(board):
        for y, each in enumerate(row):
            if each == 'R':
                que.append((x, y, 0))
    visited = set()
    while que:
        x, y, length = que.pop(0)
        if (x, y) in visited:
            continue
        if board[x][y] == 'G':
            return length
        visited.add((x, y))
        for diff_x, diff_y in ((0, 1), (0, -1), (1, 0), (-1, 0)):
            now_x, now_y = x, y
            while True:
                next_x, next_y = now_x + diff_x, now_y + diff_y
                if 0 <= next_x < len(board) and 0 <= next_y < len(board[0]) and board[next_x][next_y] != 'D':
                    now_x, now_y = next_x, next_y
                    continue
                que.append((now_x, now_y, length + 1))
                break
    return -1

 

코틀린

class Solution {
    fun solution(board: Array<String>): Int {
        val que = ArrayDeque<Triple<Int, Int, Int>>()
        for (i in board.indices) {
            for (j in board[0].indices) {
                if (board[i][j] == 'R')
                    que.add(Triple(i, j, 0))
            }
        }
        val visited = mutableSetOf<Pair<Int, Int>>()
        val diffs = arrayOf(0 to 1, 0 to -1, 1 to 0, -1 to 0)
        while (que.isNotEmpty()) {
            val (x, y, length) = que.removeFirst()
            if (x to y in visited)
                continue
            if (board[x][y] == 'G')
                return length
            visited.add(x to y)
            for ((diffX, diffY) in diffs) {
                var (nowX, nowY) = x to y
                while (true) {
                    val (nextX, nextY) = (nowX + diffX) to (nowY + diffY)
                    if (0 <= nextX && nextX < board.size &&
                        0 <= nextY && nextY < board[0].length && board[nextX][nextY] != 'D'
                    ) {
                        nowX = nextX
                        nowY = nextY
                        continue
                    }
                    que.add(Triple(nowX, nowY, length + 1))
                    break
                }
            }
        }
        return -1
    }
}