POJ3090

Visible Lattice Points

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 7094		Accepted: 4288

Description

A lattice point (x, y) in the first quadrant (x and y are integers greater than or equal to 0), other than the origin, is visible from the origin if the line from (0, 0) to (x, y) does not pass through any other lattice point. For example, the point (4, 2) is not visible since the line from the origin passes through (2, 1). The figure below shows the points (x, y) with 0 ≤ x, y ≤ 5 with lines from the origin to the visible points.

Write a program which, given a value for the size, N, computes the number of visible points (x, y) with 0 ≤ x, y ≤ N.

Input

The first line of input contains a single integer C (1 ≤ C ≤ 1000) which is the number of datasets that follow.

Each dataset consists of a single line of input containing a single integer N (1 ≤ N ≤ 1000), which is the size.

Output

For each dataset, there is to be one line of output consisting of: the dataset number starting at 1, a single space, the size, a single space and the number of visible points for that size.

Sample Input

Sample Output

1 2 5
2 4 13
3 5 21
4 231 32549

Source

Greater New York 2006

参见：[SDOI2008]仪仗队

#include<cstdio>
using namespace std;
const int N=1005;
int T,n,tot,phi[N],prime[N/3];
bool check[N];
void prepare(){
    phi[1]=1;n=1000;
    for(int i=2;i<=n;i++){
        if(!check[i]) prime[++tot]=i,phi[i]=i-1;
        for(int j=1;j<=tot&&i*prime[j]<=n;j++){
            check[i*prime[j]]=1;
            if(!(i%prime[j])){phi[i*prime[j]]=phi[i]*prime[j];break;}
            else phi[i*prime[j]]=phi[i]*(prime[j]-1);
        }
    }
}
int main(){
    prepare();
    scanf("%d",&T);
    for(int i=1;i<=T;i++){
        scanf("%d",&n);
        int ans=0;
        for(int j=1;j<=n;j++) ans+=phi[j];
        ans<<=1;ans|=1;
        printf("%d %d %d\n",i,n,ans);
    }
    return 0;
}

__EOF__

本文作者：shenben
本文链接：https://www.cnblogs.com/shenben/p/6527953.html
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