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QOJ

IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#134368#5437. Graph CompletingSnowNorthWA 1ms3572kbC++142.1kb2023-08-03 18:12:392023-08-03 18:12:40

Judging History

你现在查看的是最新测评结果

  • [2023-08-10 23:21:45]
  • System Update: QOJ starts to keep a history of the judgings of all the submissions.
  • [2023-08-03 18:12:40]
  • 评测
  • 测评结果:WA
  • 用时:1ms
  • 内存:3572kb
  • [2023-08-03 18:12:39]
  • 提交

answer

#include <bits/stdc++.h>
#define mod 998244353
using namespace std;

const int N = 5005;
const int M = N << 1;
using ll = long long ;

struct Edge {
	int to, nxt;
}edge[M];

int n, m, _u[N], _v[N], head[N], cnt = 1;
int low[N], dfn[N], tim;
stack<int> st;
int bl[N], num[N], tot;
int two[M], siz[N], f[N][N], g[N];

void conn(int u, int v) {
	edge[++cnt] = {v, head[u]};
	head[u] = cnt;
}

void tarjan(int u, int inEg) {
	low[u] = dfn[u] = ++tim;
	st.push(u);
	for (int i = head[u]; i; i = edge[i].nxt) {
		int v = edge[i].to;
		if (!dfn[v]) {
			tarjan(v, i);
			low[u] = min(low[u], low[v]);
		} else if (i != (inEg ^ 1))
			low[u] = min(low[u], dfn[v]);
	}
	if (low[u] == dfn[u]) {
		++tot;
		while (true) {
			int t = st.top(); st.pop();
			bl[t] = tot;
			siz[tot]++;
			if (t == u) break ;
		}
	}
}

void dfs(int u, int rt) {
	f[u][siz[u]] = two[num[u]];
	for (int i = head[u]; i; i = edge[i].nxt) {
		int v = edge[i].to;
		if (v == rt) continue ;
		dfs(v, u);
		for (int i = 0; i <= siz[u]; i++) g[i] = f[u][i], f[u][i] = 0;
		for (int i = 0; i <= siz[u]; i++) {
			for (int j = 0; j <= siz[v]; j++) {
				(f[u][i + j] += (ll)g[i] * f[v][j] % mod * two[num[u] * num[v] - 1]) %= mod;
				(f[u][i] += mod - (ll)g[i] * f[v][j] % mod) %= mod;
			}
		}
		siz[u] += siz[v];
	}
}

void solve() {
	cin >> n >> m;
	
	two[0] = 1;
	for (int i = 1; i < M; i++) two[i] = two[i - 1] * 2 % mod;
	
	for (int i = 1; i <= m; i++) {
		cin >> _u[i] >> _v[i];
		conn(_u[i], _v[i]);
		conn(_v[i], _u[i]);
	}
	
	tarjan(1, 0);
	
	cnt = 0;
	memset(head, 0, sizeof head);
	for (int i = 1; i <= m; i++) {
		if (bl[_u[i]] == bl[_v[i]]) num[bl[_u[i]]]++;
		else {
			conn(bl[_u[i]], bl[_v[i]]);
			conn(bl[_v[i]], bl[_u[i]]);
		}
	}
	
	for (int i = 1; i <= tot; i++) {
		num[i] = siz[i] * (siz[i] - 1) / 2 - num[i];
	}
	dfs(1, 0);
	
	int ans = 0;
	for (int i = 0; i <= n; i++) {
		ans += f[1][i];
		if (ans >= mod) ans -= mod;
	}
	cout << ans << '\n';
}

signed main() {
	ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	solve();
	return 0;
}


Details

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Test #1:

score: 100
Accepted
time: 1ms
memory: 3564kb

input:

3 2
1 2
2 3

output:

1

result:

ok 1 number(s): "1"

Test #2:

score: 0
Accepted
time: 1ms
memory: 3572kb

input:

4 4
1 2
2 3
3 4
4 1

output:

4

result:

ok 1 number(s): "4"

Test #3:

score: -100
Wrong Answer
time: 1ms
memory: 3568kb

input:

2 1
1 2

output:

998244352

result:

wrong answer 1st numbers differ - expected: '0', found: '998244352'