POJ-2739 Sum of Consecutive Prime Numbers
Sum of Consecutive Prime Numbers
问有多少个连续的素数区间和为n
尺取模板
不用素数筛可能会T
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <string>
#include <queue>
#include <functional>
#include <map>
#include <set>
#include <cmath>
#include <cstring>
#include <deque>
#include <stack>
using namespace std;
typedef long long ll;
#define pii pair<int, int>
const ll maxn = 2e5 + 10;
const ll inf = 1e17 + 10;
int p[maxn], tp = 0, prime[maxn];
void init()
{
prime[0] = prime[1] = 1;
for(int i=2; i*i<maxn; i++)
{
if(prime[i]) continue;
for(int j=i+i; j<maxn; j+=i)
prime[j] = 1;
}
for(int i=2; i<maxn; i++)
if(prime[i] == 0)
p[tp++] = i;
}
int main()
{
init();
int n;
while(scanf("%d", &n) != EOF && n)
{
int now = 0, l = 0, r = 0, ans = 0;
while(1)
{
while(now < n)
now += p[r++];
if(now == n) ans++;
if(r - l == 1 && now > n) break;
now -= p[l++];
}
printf("%d\n", ans);
}
return 0;
}