求助！WA30pts

#include <bits/stdc++.h>
using namespace std;
const int N = (1 << 20) + 100;
int n;
double res, f[2][N], p[N];
void sos(double *g) {
	for(int s = 0; s < n; ++s)
		for(int i = 0; i < (1 << n); ++i)
			if(i >> s & 1) 
				g[i] += g[i ^ (1 << s)];
	return;
}
void isos(double *g) {
	for(int s = 0; s < n; ++s)
		for(int i = 0; i < (1 << n); ++i)
			if(i >> s & 1) 
				g[i] -= g[i ^ (1 << s)];
	return;
}
signed main() {
    ios :: sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    f[0][0] = 1;
    cin >> n;
    for(int i = 0; i < (1 << n); ++i) cin >> p[i];
    sos(p);
    for(int i = 1; ; ++i) {
    	if(1. * clock() / CLOCKS_PER_SEC > 0.95) break;
    	sos(f[i - 1 & 1]);
    	for(int j = 0; j < (1 << n); ++j) f[i & 1][j] = f[i - 1 & 1][j] * p[j];
		isos(f[i & 1]);
		res += i * f[i & 1][(1 << n) - 1];
		f[i & 1][(1 << n) - 1] = 0; 
	}
	if(res == 0) cout << "INF\n";
	else cout << fixed << setprecision(10) << res << '\n';
    return 0;
}