10.21: bfs(리코쳇 로봇)

programmers/리코쳇 로봇.js

@@ -0,0 +1,51 @@
+// 리코쳇 로봇 : bfs
+function solution(board) {
+  var answer = -1;
+  const q = [];
+  const dir = [
+    [-1, 0],
+    [0, 1],
+    [1, 0],
+    [0, -1],
+  ];
+  board = board.map((v) => v.split(""));
+  const n = board.length;
+  const m = board[0].length;
+  for (let i = 0; i < n; i++) {
+    for (let j = 0; j < m; j++) {
+      if (board[i][j] === "R") q.push([[i, j], 0]);
+    }
+  }
+  // bfs
+  while (q.length !== 0) {
+    const top = q[0];
+    q.shift(); // 시간 복잡도 고려
+    // G라면 break;
+    if (board[top[0][0]][top[0][1]] === "G") {
+      answer = top[1];
+      break;
+    }
+    board[top[0][0]][top[0][1]] = "V";
+    for (let i = 0; i < dir.length; i++) {
+      // R위치 최신화
+      const next = [top[0][0], top[0][1]];
+      while (
+        !(
+          next[0] + dir[i][0] < 0 ||
+          next[0] + dir[i][0] >= n ||
+          next[1] + dir[i][1] < 0 ||
+          next[1] + dir[i][1] >= m ||
+          board[next[0] + dir[i][0]][next[1] + dir[i][1]] === "D"
+        )
+      ) {
+        next[0] = next[0] + dir[i][0];
+        next[1] = next[1] + dir[i][1];
+      }
+      if (next[0] < 0 || next[0] >= n || next[1] < 0 || next[1] >= m) continue;
+      if (board[next[0]][next[1]] === "D" || board[next[0]][next[1]] === "V")
+        continue;
+      q.push([next, top[1] + 1]);
+    }
+  }
+  return answer;
+}