……下面是全部的代码
# include <bits/stdc++.h>
using namespace std;
int n,m,k;
int l,r,t;
int main()
{
scanf("%d%d",&n,&m);
for(int i=1;i<=n;i++)
{
scanf("%d%d",&l,&r);
if(l<1||l>m||r<1||r>m)
{
cout<<"Crossing the line"<<endl;
continue;
}
t=0;
for(int j=l;j<=r;j++)
{
k=0;
for(int h=2;h*h<=j;h++)
{
if(j%h==0)
k=1;
}
if(k==0)t++;
}
if(l==1)t--;
cout<<t<<endl;
}
return 0;
}
by Scorpio初霁 @ 2018-11-03 14:17:13
可以去百度一下线性筛,时间效率$O(n)$
by Gavin·Olivia @ 2018-11-03 14:18:04
```
#include<stdio.h>
int n,i,srx[101],sry[101],j;
int main()
{
scanf("%d",&n);
for(i=1;i<=n;i++)
scanf("%d%d",&srx[i],&sry[i]);
for(i=1;i<n;i++)
for(j=i+1;j<=n;j++)
if(srx[i]+sry[i]==srx[j]&&srx[j]+sry[j]==srx[i])
{printf("YES");
return 0;}
printf("NO");
return 0;
}
```
by 不到前10不改名 @ 2018-11-03 14:18:10
代码如下(自己打的):
```cpp
pd[1]=true;
for(i=2;i<=n;i++)
{
if(!pd[i]) prm[++cnt]=i;
for(j=1;j<=cnt;j++)
{
k=prm[j]*i; if(k>n)break;
pd[k]=true; small[k]=j;
if(small[i]==j) break;
}
}
```
by Gavin·Olivia @ 2018-11-03 14:22:29
中国剩余定理
by w23c3c3 @ 2018-11-03 14:27:58