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1 초 128 MB 63 18 15 46.875%

문제

오늘은 직사각형 모양의 방을 로봇 청소기를 이용해 청소하려고 한다. 이 로봇 청소기는 유저가 직접 경로를 설정할 수 있다.

방은 크기가 1×1인 정사각형 칸으로 나누어져 있으며, 로봇 청소기의 크기도 1×1이다. 칸은 깨끗한 칸과 더러운 칸으로 나누어져 있으며, 로봇 청소기는 더러운 칸을 방문해서 깨끗한 칸으로 바꿀 수 있다.

일부 칸에는 가구가 놓여져 있고, 가구의 크기도 1×1이다. 로봇 청소기는 가구가 놓여진 칸으로 이동할 수 없다. 

로봇은 한 번 움직일 때, 인접한 칸으로 이동할 수 있다. 또, 로봇은 같은 칸을 여러 번 방문할 수 있다.

방의 정보가 주어졌을 때, 더러운 칸을 모두 깨끗한 칸으로 만드는데 필요한 이동 횟수의 최소값을 구하는 프로그램을 작성하시오.

입력

입력은 여러 개의 테스트케이스로 이루어져 있다.

각 테스트 케이스의 첫째 줄에는 방의 가로 크기 w와 세로 크기 h가 주어진다. (1 ≤ w, h ≤ 20) 둘째 줄부터 h개의 줄에는 방의 정보가 주어진다. 방의 정보는 4가지 문자로만 이루어져 있으며, 각 문자의 의미는 다음과 같다.

  • .: 깨끗한 칸
  • *: 더러운 칸
  • x: 가구
  • o: 로봇 청소기의 시작 위치

더러운 칸의 개수는 10개를 넘지 않으며, 로봇 청소기의 개수는 항상 하나이다.

입력의 마지막 줄에는 0이 두 개 주어진다.

출력

각각의 테스트 케이스마다 더러운 칸을 모두 깨끗한 칸으로 바꾸는 이동 횟수의 최소값을 한 줄에 하나씩 출력한다. 만약, 방문할 수 없는 더러운 칸이 존재하는 경우에는 -1을 출력한다.

예제 입력 1

7 5
.......
.o...*.
.......
.*...*.
.......
15 13
.......x.......
...o...x....*..
.......x.......
.......x.......
.......x.......
...............
xxxxx.....xxxxx
...............
.......x.......
.......x.......
.......x.......
..*....x....*..
.......x.......
10 10
..........
..o.......
..........
..........
..........
.....xxxxx
.....x....
.....x.*..
.....x....
.....x....
0 0

예제 출력 1

8
49
-1

힌트

[{"problem_id":"4991","problem_lang":"0","title":"\ub85c\ubd07 \uccad\uc18c\uae30","description":"<p>\uc624\ub298\uc740 \uc9c1\uc0ac\uac01\ud615 \ubaa8\uc591\uc758 \ubc29\uc744 \ub85c\ubd07 \uccad\uc18c\uae30\ub97c \uc774\uc6a9\ud574 \uccad\uc18c\ud558\ub824\uace0 \ud55c\ub2e4. \uc774 \ub85c\ubd07 \uccad\uc18c\uae30\ub294 \uc720\uc800\uac00 \uc9c1\uc811 \uacbd\ub85c\ub97c \uc124\uc815\ud560 \uc218 \uc788\ub2e4.<\/p>\r\n\r\n<p>\ubc29\uc740 \ud06c\uae30\uac00 1&times;1\uc778 \uc815\uc0ac\uac01\ud615 \uce78\uc73c\ub85c \ub098\ub204\uc5b4\uc838 \uc788\uc73c\uba70, \ub85c\ubd07 \uccad\uc18c\uae30\uc758 \ud06c\uae30\ub3c4 1&times;1\uc774\ub2e4. \uce78\uc740 \uae68\ub057\ud55c \uce78\uacfc \ub354\ub7ec\uc6b4 \uce78\uc73c\ub85c \ub098\ub204\uc5b4\uc838 \uc788\uc73c\uba70, \ub85c\ubd07 \uccad\uc18c\uae30\ub294 \ub354\ub7ec\uc6b4 \uce78\uc744 \ubc29\ubb38\ud574\uc11c \uae68\ub057\ud55c \uce78\uc73c\ub85c \ubc14\uafc0 \uc218 \uc788\ub2e4.<\/p>\r\n\r\n<p>\uc77c\ubd80 \uce78\uc5d0\ub294 \uac00\uad6c\uac00 \ub193\uc5ec\uc838 \uc788\uace0, \uac00\uad6c\uc758 \ud06c\uae30\ub3c4 1&times;1\uc774\ub2e4. \ub85c\ubd07 \uccad\uc18c\uae30\ub294 \uac00\uad6c\uac00 \ub193\uc5ec\uc9c4 \uce78\uc73c\ub85c \uc774\ub3d9\ud560 \uc218 \uc5c6\ub2e4.&nbsp;<\/p>\r\n\r\n<p>\ub85c\ubd07\uc740 \ud55c \ubc88 \uc6c0\uc9c1\uc77c \ub54c, \uc778\uc811\ud55c \uce78\uc73c\ub85c \uc774\ub3d9\ud560 \uc218 \uc788\ub2e4. \ub610, \ub85c\ubd07\uc740 \uac19\uc740 \uce78\uc744 \uc5ec\ub7ec \ubc88 \ubc29\ubb38\ud560 \uc218 \uc788\ub2e4.<\/p>\r\n\r\n<p>\ubc29\uc758 \uc815\ubcf4\uac00 \uc8fc\uc5b4\uc84c\uc744 \ub54c, \ub354\ub7ec\uc6b4 \uce78\uc744 \ubaa8\ub450 \uae68\ub057\ud55c \uce78\uc73c\ub85c \ub9cc\ub4dc\ub294\ub370 \ud544\uc694\ud55c \uc774\ub3d9 \ud69f\uc218\uc758 \ucd5c\uc18c\uac12\uc744 \uad6c\ud558\ub294 \ud504\ub85c\uadf8\ub7a8\uc744 \uc791\uc131\ud558\uc2dc\uc624.<\/p>\r\n","input":"<p>\uc785\ub825\uc740 \uc5ec\ub7ec \uac1c\uc758 \ud14c\uc2a4\ud2b8\ucf00\uc774\uc2a4\ub85c \uc774\ub8e8\uc5b4\uc838 \uc788\ub2e4.<\/p>\r\n\r\n<p>\uac01 \ud14c\uc2a4\ud2b8 \ucf00\uc774\uc2a4\uc758 \uccab\uc9f8 \uc904\uc5d0\ub294 \ubc29\uc758 \uac00\ub85c \ud06c\uae30 w\uc640 \uc138\ub85c \ud06c\uae30 h\uac00 \uc8fc\uc5b4\uc9c4\ub2e4. (1 &le; w, h &le; 20) \ub458\uc9f8 \uc904\ubd80\ud130 h\uac1c\uc758 \uc904\uc5d0\ub294 \ubc29\uc758 \uc815\ubcf4\uac00 \uc8fc\uc5b4\uc9c4\ub2e4. \ubc29\uc758 \uc815\ubcf4\ub294 4\uac00\uc9c0 \ubb38\uc790\ub85c\ub9cc \uc774\ub8e8\uc5b4\uc838 \uc788\uc73c\uba70, \uac01 \ubb38\uc790\uc758 \uc758\ubbf8\ub294 \ub2e4\uc74c\uacfc \uac19\ub2e4.<\/p>\r\n\r\n<ul>\r\n\t<li><code>.<\/code>: \uae68\ub057\ud55c \uce78<\/li>\r\n\t<li><code>*<\/code>: \ub354\ub7ec\uc6b4 \uce78<\/li>\r\n\t<li><code>x<\/code>: \uac00\uad6c<\/li>\r\n\t<li><code>o<\/code>: \ub85c\ubd07 \uccad\uc18c\uae30\uc758 \uc2dc\uc791 \uc704\uce58<\/li>\r\n<\/ul>\r\n\r\n<p>\ub354\ub7ec\uc6b4 \uce78\uc758 \uac1c\uc218\ub294 10\uac1c\ub97c \ub118\uc9c0 \uc54a\uc73c\uba70, \ub85c\ubd07 \uccad\uc18c\uae30\uc758 \uac1c\uc218\ub294 \ud56d\uc0c1 \ud558\ub098\uc774\ub2e4.<\/p>\r\n\r\n<p>\uc785\ub825\uc758 \ub9c8\uc9c0\ub9c9 \uc904\uc5d0\ub294 0\uc774 \ub450 \uac1c \uc8fc\uc5b4\uc9c4\ub2e4.<\/p>\r\n","output":"<p>\uac01\uac01\uc758 \ud14c\uc2a4\ud2b8 \ucf00\uc774\uc2a4\ub9c8\ub2e4 \ub354\ub7ec\uc6b4 \uce78\uc744 \ubaa8\ub450 \uae68\ub057\ud55c \uce78\uc73c\ub85c \ubc14\uafb8\ub294 \uc774\ub3d9 \ud69f\uc218\uc758 \ucd5c\uc18c\uac12\uc744 \ud55c \uc904\uc5d0 \ud558\ub098\uc529 \ucd9c\ub825\ud55c\ub2e4. \ub9cc\uc57d, \ubc29\ubb38\ud560 \uc218 \uc5c6\ub294&nbsp;\ub354\ub7ec\uc6b4 \uce78\uc774 \uc874\uc7ac\ud558\ub294 \uacbd\uc6b0\uc5d0\ub294 -1\uc744 \ucd9c\ub825\ud55c\ub2e4.<\/p>\r\n","hint":"","original":"0","problem_lang_code":"\ud55c\uad6d\uc5b4"},{"problem_id":"4991","problem_lang":"1","title":"Cleaning Robot","description":"<p>Here, we want to solve path planning for a mobile robot cleaning a rectangular room floor with furniture.<\/p>\r\n\r\n<p>Consider the room floor paved with square tiles whose size fits the cleaning robot (1 &times; 1). There are &#39;clean tiles&#39; and &#39;dirty tiles&#39;, and the robot can change a &#39;dirty tile&#39; to a &#39;clean tile&#39; by visiting the tile. Also there may be some obstacles (furniture) whose size fits a tile in the room. If there is an obstacle on a tile, the robot cannot visit it. The robot moves to an adjacent tile with one move. The tile onto which the robot moves must be one of four tiles (i.e., east, west, north or south) adjacent to the tile where the robot is present. The robot may visit a tile twice or more.<\/p>\r\n\r\n<p>Your task is to write a program which computes the minimum number of moves for the robot to change all &#39;dirty tiles&#39; to &#39;clean tiles&#39;, if ever possible.<\/p>\r\n","input":"<p>The input consists of multiple maps, each representing the size and arrangement of the room. A map is given in the following format.<\/p>\r\n\r\n<pre>\r\nw h\r\nc<sub>11<\/sub> c<sub>12<\/sub> c<sub>13<\/sub> ... c<sub>1w<\/sub>\r\nc<sub>21<\/sub> c<sub>22<\/sub> c<sub>23<\/sub> ... c<sub>2w<\/sub>\r\n...\r\nc<sub>h1<\/sub> c<sub>h2<\/sub> c<sub>h3<\/sub> ... c<sub>hw<\/sub><\/pre>\r\n\r\n<p>The integers w and h are the lengths of the two sides of the floor of the room in terms of widths of floor tiles. w and h are less than or equal to 20. The character c<sub>yx<\/sub> represents what is initially on the tile with coordinates (x, y) as follows.<\/p>\r\n\r\n<ul>\r\n\t<li>&#39;<code>.<\/code>&#39; : a clean tile<\/li>\r\n\t<li>&#39;<code>*<\/code>&#39; : a dirty tile&nbsp;<\/li>\r\n\t<li>&#39;<code>x<\/code>&#39; : a piece of furniture (obstacle)&nbsp;<\/li>\r\n\t<li>&#39;<code>o<\/code>&#39; : the robot (initial position)<\/li>\r\n<\/ul>\r\n\r\n<p>In the map the number of &#39;dirty tiles&#39; does not exceed 10. There is only one &#39;robot&#39;.<\/p>\r\n\r\n<p>The end of the input is indicated by a line containing two zeros.<\/p>\r\n","output":"<p>For each map, your program should output a line containing the minimum number of moves. If the map includes &#39;dirty tiles&#39; which the robot cannot reach, your program should output -1.<\/p>\r\n","hint":"","original":"1","problem_lang_code":"\uc601\uc5b4"}]