CodeForces 623D Birthday (贪心)

//
//  main.cpp
//  Main
//
//  Created by czk on 16/7/13.
//  Copyright © 2016年 czk. All rights reserved.
//

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

#define N 120

double p
;
int n;
int c
;
double pp
;
double P[3000030];

int main() {
scanf("%d", &n);
for(int i = 1; i <= n; ++i) {
scanf("%lf", &p[i]);
p[i] /= 100;
}
for(int i = 1; i <= n; ++i) {
pp[i] = 1 - p[i];
}
double ans = 0;
for(int t = n; t <= 300000; ++t) {

P[t] = 1;
for(int i = 1; i <= n; ++i) {
P[t] *= 1 - pp[i];
}
ans += t * (P[t] - P[t - 1]);
int u = -1;
double mx = 0;
double sum = 1;
for(int i = 1; i <= n; ++i) {
sum *= 1 - pp[i];
}
for(int i = 1; i <= n; ++i) {
if(sum / (1 - pp[i]) * pp[i] * p[i] > mx) {
mx = sum / (1 - pp[i]) * pp[i] * p[i];
u = i;
}
}
c[u]++;
pp[u] *= 1 - p[u];

}
printf("%.12lf\n", ans);

return 0;
}