Primes Problem
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 921 Accepted Submission(s): 420
Problem Description
Given a number n, please count how many tuple(p1, p2, p3) satisfied that p1<=p2<=p3, p1,p2,p3 are primes and p1 + p2 + p3 = n.
Input
Multiple test cases(less than 100), for each test case, the only line indicates the positive integer
n(n≤10000)
.
Output
For each test case, print the number of ways.
Sample Input
3 9
Sample Output
0 2
//三维化为二维
#include<iostream>
#include<stdio.h>
#define M 10001
using namespace std;
int prime[M];
int k;
void getPrime()
{
int i,j;
memset(prime,0,sizeof(prime));//0表示素数
for(i=2;i<M;i++)
{
if(!prime[i])
{
for(j=2*i;j<M;j+=i)
prime[j]=1;
}
}
}
int main(){
int i,j,z,n,count;
getPrime();
while(scanf("%d",&n)!=EOF)
{
count=0;
for(i=2;i<=n/3;i++)
for(j=i;j<=(n-i)/2;j++)
if(!prime[i]&&!prime[j]&&!prime[n-i-j])
count++;
printf("%d\n",count);
}
return 0;
}