HDU5935 Car（精度水题）

/* ***********************************************
Author        :devil
************************************************ */
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <stack>
#include <map>
#include <string>
#include <time.h>
#include <cmath>
#include <stdlib.h>
#define LL long long
#define rep(i,a,b) for(int i=a;i<=b;i++)
#define dep(i,a,b) for(int i=a;i>=b;i--)
#define ou(a) printf("%d\n",a)
#define pb push_back
#define mkp make_pair
template<class T>inline void rd(T &x)
{
    char c=getchar();
    x=0;
    while(!isdigit(c))c=getchar();
    while(isdigit(c))
    {
        x=x*10+c-‘0‘;
        c=getchar();
    }
}
#define IN freopen("in.txt","r",stdin);
#define OUT freopen("out.txt","w",stdout);
using namespace std;
const int inf=0x3f3f3f3f;
const int mod=1e9+7;
const int N=1e5+10;
int t,n,a[N];
int main()
{
#ifndef ONLINE_JUDGE
//IN
#endif
    int cas=0;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(int i=1;i<=n;i++) scanf("%d",&a[i]);
        LL ans=1;
        LL zi=a[n]-a[n-1],mu=1;
        for(int i=n-1;i>=1;i--)
        {
            LL d=a[i]-a[i-1];
            if(zi>d*mu)
            {
                mu=1;
                zi=d;
                ans++;
            }
            else if(d*mu%zi==0) ans=ans+d*mu/zi;
            else
            {
                LL t=d*mu/zi+1;
                int tmp=__gcd(d,t);
                zi=d/tmp;
                mu=t/tmp;
                ans=ans+t;
            }
        }
        printf("Case #%d: %lld\n",++cas,ans);
    }
    return 0;
}