Submission #1450072

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Source Code Expand

#include <bits/stdc++.h>
#include <random>
using namespace std;

#define rep(i, N) for (int i = 0; i < N; i++)
#define pb push_back

typedef long long ll;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;

int sign = 0;

void dfs(int u, vector<multiset<int> >& G, vector<int>& a, set<int>& st) {
	int N = a.size();
	if (G[u].empty()) {
		st.erase(u);
		return;
	}
	int v = *G[u].begin();
	if (v >= 0) {
		auto it = G[u].find(v);
		G[u].erase(it);
		it = G[v].find(u);
		G[v].erase(it);
		a[u]++, a[v]--;
		dfs(v, G, a, st);
	}
	else {
		v = ~v;
		auto it = G[u].find(~v);
		G[u].erase(it);
		it = G[v].find(~u);
		G[v].erase(it);
		a[u]--, a[v]++;
		dfs(v, G, a, st);
	}
}

int main() {
	int N; cin >> N;
	vector<int> p(N), q(N);
	rep(u, N) scanf("%d", &p[u]), p[u]--;
	rep(u, N) scanf("%d", &q[u]), q[u]--;
	vector<multiset<int> > G(N + 1);
	rep(u, N) if (p[u] != -2) {
		int v = p[u];
		G[u].insert(v);
		G[v].insert(u);
	}
	else G[u].insert(N), G[N].insert(u);
	rep(u, N) if (q[u] != -2) {
		int v = q[u];
		G[u].insert(~v);
		G[v].insert(~u);
	}
	else G[u].insert(~N), G[N].insert(~u);
	rep(u, N) if (G[u].size() % 2) {
		cout << "IMPOSSIBLE" << endl;
		return 0;
	}
	set<int> st;
	rep(u, N + 1) st.insert(u);
	vector<int> a(N + 1);
	while (st.size()) {
		int u = *st.begin();
		dfs(u, G, a, st);
	}
	cout << "POSSIBLE" << endl;
	rep(u, N) printf("%d ", a[u] / 2);
	cout << endl;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:43:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  rep(u, N) scanf("%d", &p[u]), p[u]--;
                                      ^
./Main.cpp:44:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  rep(u, N) scanf("%d", &q[u]), q[u]--;
                                      ^

Judge Result