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HDU 5139 Formula 离线处理

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Formula

Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 361    Accepted Submission(s): 151


Problem Description
f(n)=(i=1nin?i+1)%1000000007
You are expected to write a program to calculate f(n) when a certain n is given.
 

Input
Multi test cases (about 100000), every case contains an integer n in a single line. 
Please process to the end of file.

[Technical Specification]
1n10000000
 

Output
For each n,output f(n) in a single line.
 

Sample Input
2 100
 

Sample Output
2 148277692
 

Source
BestCoder Round #21
 

找规律
f(1)=1
f(2)=1*1*2=(1)*(1*2)=1!*2!
f(3)=1*1*1*2*2*3=(1)*(1*2)*(1*2*3)=1!*2!*3!
式子可以简化为 f(n)=i=1n(n!)%MOD,直接打表不行,会超内存,可以对数据进行离线处理。排好序之后从小到大暴力。ClogC+10000000 ,C为case数目。
//702MS	4228K
#include<stdio.h>
#include<string.h>
#include<algorithm>
#define ll __int64
#define M 1000000007
using namespace std;
struct Keng
{
    ll val;
    int pos;
} p[100007],ans[100007];
int cmp(Keng a,Keng b)
{
    return a.val<b.val;
}
int main()
{
    ll anss=1,b=1,n;
    int k=0;
    while(scanf("%I64d",&n)!=EOF)
        p[++k].val=n,p[k].pos=k;
    sort(p+1,p+k+1,cmp);
    p[0].val=0;
    for(int i=1; i<=k; i++)
    {
        for(int j=p[i-1].val+1;j<=p[i].val;j++)
        {
            b=(b*j)%M;
            anss=(b*anss)%M;
        }
        ans[p[i].pos].val=anss;
    }
    for(int i=1; i<=k; i++)
        printf("%I64d\n",ans[i].val);
    return 0;
}


HDU 5139 Formula 离线处理