Submission #19242

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Source Code Expand

#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <numeric>
#include <cassert>
using namespace std;
static const double EPS = 1e-10;
typedef long long ll;
#define rep(i,n) for(int i=0;i<n;i++)
#define rev(i,n) for(int i=n-1;i>=0;i--)
#define all(a) a.begin(),a.end()
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define SS stringstream
#define DBG1(a) rep(_X,sz(a)){printf("%d ",a[_X]);}puts("");
#define DBG2(a) rep(_X,sz(a)){rep(_Y,sz(a[_X]))printf("%d ",a[_X][_Y]);puts("");}
#define bitcount(b) __builtin_popcount(b)
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)

#define delete(a,n) a.erase(remove(all(a),n),a.end())
template<typename T, typename S> vector<T>& operator<<(vector<T>& a, S b) { a.push_back(b); return a; }
template<typename T> void operator>>(vector<T>& a, int b) {while(b--)if(!a.empty())a.pop_back();}
bool isprime(int n){ if(n<2)return false; for(int i=2;i*i<=n;i++)if(n%i==0)return false; return true;}
ll b_pow(ll x,ll n){return n ? b_pow(x*x,n/2)*(n%2?x:1) : 1ll;}
string itos(int n){stringstream ss;ss << n;return ss.str();}

int N,K;
int a[20];
bool bad[20][20];

bool simulate(void){
	for(int i = 0 ; i < N ; i++) a[i] = i;
	for(int i = 0 ; i < K ; i++){
		int x = rand() % N, y = (x + rand() % (N - 1) + 1) % N;
		swap(a[x],a[y]);
	}
	for(int i = 0 ; i < N ; i++) if( bad[a[i]][a[(i+1)%N]] ) return false;
	return true;
}

int main(){
	ios_base::sync_with_stdio(false);
	
	int M;
	cin >> N >> M >> K;
	
	for(int i = 0 ; i < M ; i++){
		int x,y;
		cin >> x >> y;
		bad[x][y] = bad[y][x] = true;
	}
	
	clock_t start = clock();
	
	int cnt = 0;
	int iter;
	for(iter = 0 ; ; iter++){
		if( iter % 100000 == 0 ){
			double t = (double)(clock() - start) / CLOCKS_PER_SEC;
			if(t > 9.0) break;
		}
		if(simulate()) cnt++;
	}
	
//	cout << cnt << ' ' << iter << endl;
	double ans = (double)cnt / iter;
	printf("%.9f\n",ans);
}

Submission Info

Judge Result