Csu1030 prime number slot

Description

 

Two Adjacent prime numbersPAndP + nBetweenN-A sequence composed of one continuous sum is called the lengthN. For example, limit 24, 25, 26, 27, 28 › is a prime number slot with a length of 6 between prime number 23 and prime number 29.

Your task is to write a program to calculate the inclusion integerKThe length of the prime number slot. IfKIt is a prime number, so it is considered to containKThe length of the prime number slot is 0.

Input

 

The first line is a number.NIndicates the number of data to be tested. There areNRow. Each row is a positive integer.K,KThe Second Prime Number (that is, 100,000) that is greater than 1 and less than or equal ).

Output

 

For each input partK, All correspond to the output of a non-negative integer, indicating to containKThe length of the prime number slot. Each non-negative integer occupies a row.

 

This topic requires no time-out. Therefore, you need to use the prime number tabulation method to locate the qualified prime number. The final result is obtained by subtracting the subscript.

 

The Code is as follows:

 1 #include <iostream> 2 #include<stdio.h> 3 #include<cstring> 4 #include<cmath> 5 using namespace std; 6  7 #define MAXN 1300000 8 int p[MAXN]; 9 10 void getPrim()11 {12     memset(p,1,sizeof(p));13     int n = (int)(sqrt(MAXN+0.5));14     for(int i=2;i<=n;i++){15         for(int j=i+i;j<=MAXN;j+=i) p[j]=0;16     }17 }18 int main()19 {20     int T,k;21     cin>>T;22     getPrim();23     while(T--){24        cin>>k;25 26        int top=k,floor=k;27        while(p[top]==0) top++;28        while(p[floor]==0) floor--;29        cout<<top-floor<<endl;30 31     }32     return 0;33 }