UVA1210 consecutive prime numbers Sum of Consecutive Prime Numbers

UVA1210 consecutive prime numbers Sum of Consecutive Prime Numbers swept out

Sweep out all prime numbers within 1 to 10000, and recording a prime number prefixes.

Violence and O (n ^ 2).

There is a train of thought is to use the queue has been added up, the team is not satisfied, O (n) can be

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 
 5 const int MAXN=1e4+5;
 6 
 7 ll sum[MAXN];
 8 
 9 bool is_prime[MAXN];
10 int prime[MAXN];
11 int sieve(int n)
12 {
13     for(int i=0;i<=n;i++)
14         is_prime[i]=true;
15     is_prime[0]=is_prime[1]=false;
16     int p=0;
17     for(int i=1;i<=n;i++)
18     {
19         if(is_prime[i])
20         {
21             prime[++p]=i;
22             for(int j=i*2;j<=n;j+=i)
23             {
24                 is_prime[j]=false;
25             }
26         }
27     }
28     return p;
29 }
30 
31 
32 int main()
33 {
34     int n;
35     int p=sieve(10000);
36     //freopen("a.txt","r",stdin);
37     for(int i=1;i<=p;i++)
38     {
39         sum[i]+=prime[i]+sum[i-1];
40     }
41     while(cin>>n)
42     {
43         ll ans=0;
44         if(n==0) break;
45         for(int i=1;i<=p;i++)
46         {
47             if(prime[i]>n) break;
48             for(int j=i;j<=p;j++)
49             {
50                 if(sum[j]-sum[i-1]==n) ans++;
51             }
52         }
53         cout <<ans<<endl;
54     }
55     return 0;
56 }