usaco 1.43Arithmetic Progressions

直接枚举a1和d。

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 1 /*

 2   ID: your_id_here

 3   PROG: ariprog

 4   LANG: C++

 5   */

 6 #include <iostream>

 7 #include<cstdio>

 8 #include<cstring>

 9 using namespace std;

10 int f[200000];

11 int main()

12 {

13     freopen("ariprog.in","r",stdin);

14     freopen("ariprog.out","w",stdout);

15     int i,j,n,m,k,a,d,flag;

16     f[0] = 1;

17     int ff = 0;

18     cin>>n>>m;

19     for(i = 0 ; i <= m ; i++)

20     for(j = 1; j <= m ; j++)

21     f[i*i+j*j] = 1;

22     for(d = 1 ; d<=2*m*m ; d++)

23     for(a = 0; ; a++)

24     {

25         if(a+(n-1)*d>2*m*m)

26         break;

27         flag = 1;

28         for(i = 0; i < n ; i++)

29         {

30             if(!f[a+i*d])

31             {

32                 flag = 0;

33                 break;

34             }

35         }

36         if(flag)

37         {

38             ff = 1;

39             cout<<a<<" "<<d<<endl;

40         }

41     }

42     if(!ff)

43     cout<<"NONE\n";

44     fclose(stdin);

45     fclose(stdout);

46     return 0;

47 }