hdu 1164 質因子分解 （篩素數模板）+ hdu 1215

#include <iostream>
#define M 100000 // [1..M]
#define clr(x, k) memset((x), (k), sizeof(x))
bool f[M];
int d[M], p=0;
void Getprime()
{
	int i, j;
	p = 0;
	clr(f, 0);
	for (i=2;i<M;++i)
	{
		if (!f[i]) d[p++] = i;
		for (j=0;(j<p && i*d[j]<M);++j)
		{
			f[i*d[j]] = 1;
			if (i % d[j] == 0) break;
		}
	}
}

int main()
{
	Getprime();
	int n,i,a[10000];
	while(scanf("%d",&n)!=EOF)
	{
		int total=0;
		for(i=0;d[i]*d[i]<=n;i++)
		{
			if(n%d[i]==0)
			{
				a[total++]=d[i];
				n/=d[i];
				while(n%d[i]==0)
				{
					a[total++]=d[i];
					n/=d[i];
				}
			}
		}
		if(n>1)
			a[total++]=n;
		printf("%d",a[0]);
		for(i=1;i<total;i++)
			printf("*%d",a[i]);
		printf("\n");
	}
	return 0;
}

#include <iostream>
using namespace std;
#define M 500003      // 01會WA


int main()
{
	int i, j, t, n, k;
	int p[M] = {0,0};
	for (i=2;i<M;++i) p[i] = 1;
	for (i=2;i<M/2;++i)  // 枚舉約數
	{
		for (j=2;j*i<M;++j)
		{
			p[j*i] += i;
		}
	}
	scanf("%d", &n);
	while (n--)
	{
		scanf("%d", &t);
		printf("%d\n", p[t]);
	}
	return 0;
}
	

 

#include <iostream>
using namespace std;
#define M 500003      // 01會WA


int main()
{
	int i, j, t, n, k;
	int p[M] = {0,0};
	for (i=2;i<M;++i) p[i] = 1;
	for (i=2;i<M/2;++i)  // 枚舉約數
	{
		for (j=2;j*i<M;++j)
		{
			p[j*i] += i;
		}
	}
	scanf("%d", &n);
	while (n--)
	{
		scanf("%d", &t);
		printf("%d\n", p[t]);
	}
	return 0;
}