git reimport

archive/2017.09/2017.09.18 - unsorted/A.java

@@ -0,0 +1,73 @@
+package chelper;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import io.InputReader;
+import io.OutputWriter;
+import misc.SimpleSavingChelperSolution;
+
+
+public class A extends SimpleSavingChelperSolution {
+
+  public void solve(int testNumber, InputReader in, OutputWriter out) {
+    wrapSolve(testNumber, in, out);
+  }
+
+  @Override
+  public void solve(int testNumber) {
+    int n = in.nextInt();
+
+    int[] l = new int[n];
+    int[] r = new int[n];
+
+    for (int i = 0; i < n; i++) {
+      l[i] = in.nextInt() - 1;
+      r[i] = in.nextInt() - 1;
+    }
+
+    boolean[] visited = new boolean[n];
+
+    List<int[]> things = new ArrayList<>();
+
+    for (int i = 0; i < n; i++) {
+      if (visited[i]) {
+        continue;
+      }
+
+      int[] t = dfs(i, n, l, r, visited);
+      things.add(t);
+    }
+
+    for (int i = 0; i < things.size() - 1; i++) {
+      int[] t1 = things.get(i);
+      int[] t2 = things.get(i + 1);
+
+      r[t1[1]] = t2[0];
+      l[t2[0]] = t1[1];
+    }
+
+    for (int i = 0; i < n; i++) {
+      out.println((l[i] + 1) + " " + (r[i] + 1));
+    }
+  }
+
+  int[] dfs(int v, int n, int[] l, int[] r, boolean[] visited) {
+    visited[v] = true;
+
+    int leftmost = v;
+    int rightmost = v;
+
+    if (l[v] != -1 && !visited[l[v]]) {
+      int[] t = dfs(l[v], n, l, r, visited);
+      leftmost = t[0];
+    }
+
+    if (r[v] != -1 && !visited[r[v]]) {
+      int[] t = dfs(r[v], n, l, r, visited);
+      rightmost = t[1];
+    }
+
+    return new int[]{leftmost, rightmost};
+  }
+}