| 用户编号 | 8725 |
|---|---|
| 用户名称 | wqh |
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| 用户昵称 | B_Leaves |
| 3299248475@qq.com | |
| 阅读权限 | 0 |
| 所属分组 | 注册会员 |
| 等级积分 | 16 |
| 注册时间 | 2017-10-01 09:35:56 |
| 个人介绍 | #include<iostream> #include<cstdio> #include<algorithm> #include<cstring> using namespace std; double f[2001][2001]; double da[2001]; int n,k; void pre() { k=n*k; if(k%100!=0)k+=100-(k%100); k/=100; return; } long long getsum(long long num) { long long now = 1; if (!num) return 0; long long sum = 1; for (int i = 2; i <= 19; i++) { now *= 10; if (now > num) { return sum; } if (now * 2 > num) { return sum + num - now + 1; } sum += now; } } void work(long long l,long long r,int step) { double qwq=(r-l+1),QAQ; QAQ=getsum(r)-getsum(l-1); da[step]=QAQ/qwq; return ; } int main() { freopen("vangame.in","r",stdin);freopen("vangame.out","w",stdout); scanf("%d%d",&n,&k); pre(); for(int i=1;i<=n;i++) { long long l,r; scanf("%lld%lld",&l,&r); work(l,r,i); } f[0][0]=1; for(int i=1;i<=n;i++) for(int j=0;j<=i;j++) f[i][j]=f[i-1][j]*(1-da[i])+f[i-1][j-1]*da[i]; double ans=0; for(int i=k;i<=n;i++) ans+=f[n][i]; printf("%.7lf",ans); return 0; } |