Submission #1693978

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Source Code Expand

#include <bits/stdc++.h>

#define For(i, j, k) for(int i = j; i <= k; i++)
#define pb push_back
#define mp make_pair
#define x first
#define y second

using namespace std;

const int Mod = 1e9 + 7;
const int N = 210;

void add(int &x, int y){
	x += y;
	if(x >= Mod) x -= Mod;
}

void mul(int &x, int y){
	x = (long long)(x) * y % Mod;
}

int Pow(int x, int e){
	int ret = 1;
	while(e){
		if(e & 1) ret = 1ll * ret * x % Mod;
		x = 1ll * x * x % Mod;
		e >>= 1;
	}
	return ret;
}

int gcd(int x, int y){
	return !y ? x : gcd(y, x % y);
}

int n, m, k;

int Polya(int x){
	int ret = 0;
	For(i, 1, x) add(ret, Pow(k, gcd(i, x)));
	mul(ret, Pow(x, Mod - 2));
	return ret;
}

int C[N][N];

vector<int> G[N];
int ans = 1;
int dfn[N], low[N];
bool link[N][N];

stack<pair<int, int> > st;

void calc(int a, int b){
	map<int, bool> M;
	int e = 0;
	auto s = st.top();
	do{
		++e;
		s = st.top(); st.pop();
		M[s.x] = 1, M[s.y] = 1;
	}while(s.x != a || s.y != b);

//	printf("%d -> %d: %d %llu\n", a, b, e, M.size());

	if(e <= int(M.size())) mul(ans, Polya(e));
	else mul(ans, C[e + k - 1][k - 1]);
	
}

void Tarjan(int o, int f){
	static int clk = 0;
	dfn[o] = low[o] = ++clk;

	for(int v : G[o]){
		if(v == f) continue;
		if(!dfn[v]){
			st.push(mp(o, v));
			Tarjan(v, o);
			if(low[v] >= dfn[o]) calc(o, v);
			low[o] = min(low[v], low[o]);
		}
		else if(dfn[v] < dfn[o]){
			st.push(mp(o, v));
			low[o] = min(low[o], dfn[v]);
		}
	}
}

int main(){
	scanf("%d%d%d", &n, &m, &k);
	For(i, 1, m){
		int u, v;
		scanf("%d%d", &u, &v);
		G[u].pb(v), G[v].pb(u);
		link[u][v] = link[v][u] = true;
	}

	For(i, 0, m + k){
		C[i][0] = 1;
		For(j, 1, i) C[i][j] = (C[i - 1][j - 1] + C[i - 1][j]) % Mod;
	}

	For(i, 1, n) if(!dfn[i]) Tarjan(i, 0);
	printf("%d\n", ans);

	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:92:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d", &n, &m, &k);
                             ^
./Main.cpp:95:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &u, &v);
                        ^

Judge Result