Submission #1447956

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

const int N = 1234567;

vector <int> g[N], h[N];
int x[N], color[N];
int zero[N];

int dfs(int v) {
  vector <int> children;
  for (int u : g[v]) {
    children.push_back(dfs(u));
  }
  while ((int) children.size() >= 2) {
    int a = children.back();
    children.pop_back();
    int b = children.back();
    children.pop_back();
    h[a].push_back(b);
    h[b].push_back(a);
  }
  if (children.empty()) {
    return v;
  } else {
    zero[v]++;
    return children[0];
  }
}

int main() {
  int n;
  scanf("%d", &n);
  for (int it = 0; it < 2; it++) {
    for (int i = 0; i < n; i++) {
      g[i].clear();
    }
    int root = -1;
    for (int i = 0; i < n; i++) {
      int x;
      scanf("%d", &x);
      if (x == -1) {
        root = i;
      } else {
        x--;
        g[x].push_back(i);
      }
    }
    dfs(root);
  }
  for (int i = 0; i < n; i++) {
    if (zero[i] == 1) {
      puts("IMPOSSIBLE");
      return 0;
    }
  }
  for (int i = 0; i < n; i++) {
    color[i] = 0;
  }
  for (int i = 0; i < n; i++) {
    if (color[i] == 0 && zero[i] == 0) {
      int b = 0, e = 1;
      x[0] = i;
      color[i] = 1;
      while (b < e) {
        for (int j : h[x[b]]) {
          if (color[j] == 0) {
            color[j] = -color[x[b]];
            x[e++] = j;
          }
        }
        b++;
      }
    }
  }
  puts("POSSIBLE");
  for (int i = 0; i < n; i++) {
    if (i > 0) putchar(' ');
    printf("%d", color[i]);
  }
  printf("\n");
  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:34:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &n);
                  ^
./Main.cpp:42:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
       scanf("%d", &x);
                      ^

Judge Result