计蒜客button 概率

中文题意不多说,这题主要是数据太大,无法递推,所以用欧拉常数来解决

对于调和级数1/1+1/2+...+1/n=ln(n)+C+1/(2*n),C为欧拉常数,再加上ceil向上取整就可以了

#include<bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pi acos(-1.0)
#define ll long long
#define mod 1000000007
#define C 0.57721566490153286060651209
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
#define pii pair<int,int>

using namespace std;

const double g=10.0,eps=1e-12;
const int N=100000+10,maxn=200000+10,inf=0x3f3f3f3f;


int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        double n;
        scanf("%lf",&n);
        if(n<10000000)
        {
            double ans=0;
            for(double i=1;i<=n;i++)
                ans+=1.0/i;
            ans*=n;
            printf("%lld
",(ll)ceil(ans));
        }
        else
        {
            ll ans=(ll)ceil(log(n)*n+1.0/2+n*C);
            printf("%lld
",ans);
        }
    }
    return 0;
}
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原文地址:https://www.cnblogs.com/acjiumeng/p/8006150.html