Room and Moor
Time Limit: 12000/6000 MS (Java/Others) Memory Limit: 262144/262144 K (Java/Others)
Total Submission(s): 539 Accepted Submission(s): 147
Problem Description PM Room defines a sequence A = {A
1, A
2,..., A
N}, each of which is either 0 or 1. In order to beat him, programmer Moor has to construct another sequence B = {B
1, B
2,... , B
N} of the same length, which satisfies that:
Input The input consists of multiple test cases. The number of test cases T(T<=100) occurs in the first line of input.
For each test case:
The first line contains a single integer N (1<=N<=100000), which denotes the length of A and B.
The second line consists of N integers, where the ith denotes A
i.
Output Output the minimal f (A, B) when B is optimal and round it to 6 decimals.
Sample Input
4
9
1 1 1 1 1 0 0 1 1
9
1 1 0 0 1 1 1 1 1
4
0 0 1 1
4
0 1 1 1
Sample Output
1.428571
1.000000
0.000000
0.000000
Author BUPT
官方题解:

代码:
#include
#include
#include
#include
#include
using namespace std; typedef __int64 ll; struct node { double l,r; double p; } b[50010]; int main() { int T; cin>>T; int n; int s[100100]; while(T--) { cin>>n; double ans=0; bool flag=true; for(int i=0; i
>s[i]; if(s[i]==0&&flag) i--,n--; else flag=false; } int l=0,r=n-1; for(; r>=0; r--) if(s[r]!=1) { break; } int k=1; b[0].p=0; b[1].l=0,b[1].r=0; for(int i=l; i<=r; i++) { if(s[i]==1) b[k].l++; else b[k].r++; b[k].p=b[k].l/(b[k].l+b[k].r); while(b[k].p