Submission #1159180

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)


typedef long long ll;
template<int um> class UF { // from kmjp
public:
	vector<int> par;
	UF() { par = vector<int>(um, 0); rep(i, 0, um) par[i] = i; }
	int operator[](int x) { return par[x] == x ? x : par[x] = operator[](par[x]); }
	void operator()(int x, int y)
	{
		x = operator[](x); y = operator[](y);
		if (x != y) par[x] = y;
	}
};
//-----------------------------------------------------------------
ll N, M;
vector<int> E[101010];
UF<101010> uf;
//-----------------------------------------------------------------
map<int, vector<int>> divide() {
	map<int, vector<int>> m;
	rep(i, 1, N + 1) m[uf[i]].push_back(i);
	return m;
}
//-----------------------------------------------------------------
int C[101010];
int dfs(int cu, int c = 1) {
	C[cu] = c;

	int nc = 3 - c;
	int rs = 0;
	for (int to : E[cu]) {
		if (C[to] == 0) rs += dfs(to, nc);
		if (C[cu] == C[to]) return 1;
	}
	return rs;
}
//-----------------------------------------------------------------
ll calc(vector<int> v) {
	int res = dfs(v[0]);
	if (res == 0) return 2;
	return 1;
}
//-----------------------------------------------------------------
int main() {
	cin >> N >> M;
	rep(i, 0, M) {
		int u, v; scanf("%d%d", &u, &v);
		E[u].push_back(v); E[v].push_back(u);
		uf(u, v);
	}

	auto m = divide();
	ll cnt[3];
	cnt[0] = cnt[1] = cnt[2] = 0;
	for (auto p : m) {
		auto v = p.second;
		if (v.size() == 1) {
			cnt[0]++;
			continue;
		}

		if (calc(v) == 1) cnt[1]++;
		else cnt[2]++;
	}

	ll ans = 1LL * N * N - 1LL * (N - cnt[0]) * (N - cnt[0]);
	ans += 1LL * (cnt[2] + cnt[1]) * (cnt[2] + cnt[1]);
	ans += 1LL * cnt[2] * cnt[2];

	printf("%lld\n", ans);
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:51:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   int u, v; scanf("%d%d", &u, &v);
                                  ^

Judge Result