Submission #1971813

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Source Code Expand

#include <iostream>
#include <cassert>
#include <vector>
using namespace std;

long long n, a[1000], cnt; bool used[1000]; vector<pair<int, int>>x; vector<int> X[6];

void dfs(int pos) {
	if (used[pos] == true) return;
	used[pos] = true;
	for (int i = 0; i < X[pos].size(); i++) dfs(X[pos][i]);
}

int main() {
	cin >> n; assert(n <= 5);
	for (int i = 0; i < n; i++) cin >> a[i];
	for (int i = 0; i < n; i++) { for (int j = i + 1; j < n; j++) x.push_back(make_pair(i, j)); }
	for (int i = 0; i < (1 << x.size()); i++) {
		for (int j = 0; j < 6; j++) { X[j].clear(); used[j] = false; }
		for (int j = 0; j < x.size(); j++) {
			if ((i / (1 << j)) % 2 == 0) continue;
			int a1 = x[j].first, a2 = x[j].second;
			X[a1].push_back(a2); X[a2].push_back(a1);
		}
		bool flag = false;
		for (int j = 0; j < n; j++) {
			if (a[j] != X[j].size()) flag = true;
		}
		dfs(0);
		for (int j = 0; j < n; j++) {
			if (used[j] == false) flag = true;
		}
		if (flag == false) cnt++;
	}
	cout << cnt << endl;
	return 0;
}

Submission Info

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