git reimport

archive/2017.03/2017.03.04 - unsorted/C.java

@@ -0,0 +1,121 @@
+package chelper;
+
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.Queue;
+
+import io.InputReader;
+import io.OutputWriter;
+
+public class C {
+  char[] dirsOrderLabels = {'D', 'L', 'R', 'U'};
+  int[][] dirsOrder = {
+      {1, 0},  //D
+      {0, -1}, //L
+      {0, 1},  //R
+      {-1, 0}, //U
+  };
+
+  public void solve(int testNumber, InputReader in, OutputWriter out) {
+    int n = in.nextInt();
+    int m = in.nextInt();
+    int k = in.nextInt();
+
+    int startX = -1;
+    int startY = -1;
+
+    boolean[][] map = new boolean[n][m];
+
+    for (int i = 0; i < n; i++) {
+      String s = in.nextLine();
+      for (int j = 0; j < m; j++) {
+        map[i][j] = s.charAt(j) != '*';
+        if (s.charAt(j) == 'X') {
+          startX = i;
+          startY = j;
+        }
+      }
+    }
+
+    int[][] distances = new int[n][m];
+    for (int i = 0; i < n; i++) {
+      Arrays.fill(distances[i], Integer.MAX_VALUE);
+    }
+
+    Queue<int[]> queue = new LinkedList<>();
+    queue.add(new int[]{startX, startY});
+    distances[startX][startY] = 0;
+
+    while (!queue.isEmpty()) {
+      int[] posAr = queue.poll();
+      int x = posAr[0];
+      int y = posAr[1];
+
+      for (int[] dir : dirsOrder) {
+        int xx = x + dir[0];
+        int yy = y + dir[1];
+
+        if (xx < 0 || xx >= n || yy < 0 || yy >= m) {
+          continue;
+        }
+
+        if (!map[xx][yy]) {
+          continue;
+        }
+
+        if (distances[xx][yy] <= distances[x][y] + 1) {
+          continue;
+        }
+
+        distances[xx][yy] = distances[x][y] + 1;
+        queue.add(new int[]{xx, yy});
+      }
+    }
+
+    StringBuilder answer = new StringBuilder();
+
+    int x = startX;
+    int y = startY;
+    int timeLeft = k;
+
+    while (timeLeft >= distances[x][y] && timeLeft > 0) {
+      boolean ok = false;
+      for (int i = 0; i < 4; i++) {
+        int[] dir = dirsOrder[i];
+        int xx = x + dir[0];
+        int yy = y + dir[1];
+
+        if (xx < 0 || xx >= n || yy < 0 || yy >= m) {
+          continue;
+        }
+
+        if (!map[xx][yy]) {
+          continue;
+        }
+
+        if (timeLeft == distances[x][y] && distances[xx][yy] >= distances[x][y]) {
+          continue;
+        }
+
+        ok = true;
+        x = xx;
+        y = yy;
+        timeLeft--;
+        answer.append(dirsOrderLabels[i]);
+        break;
+      }
+
+      if (!ok) {
+        out.println("IMPOSSIBLE");
+        return;
+      }
+    }
+
+    if (timeLeft != 0 || x != startX || y != startY) {
+      out.println("IMPOSSIBLE");
+      return;
+    }
+
+    out.println(answer);
+  }
+}