USACO1.4.3 Arithmetic Progressions 等差数列 解题报告(枚举)

 #include <map>

    
 #include <cmath>
    
 #include <cstdio>
    
 #include <string>
    
 #include <cstring>
    
 #include <iostream>
    
 #include <algorithm>
    
 #define lowbit(a) (a&(-a))
    
 #define _mid(a,b) ((a+b)/2)
    
 #define _mem(a,b) memset(a,0,(b+3)<<2)
    
 #define fori(a) for(int i=0;i<a;i++)
    
 #define forj(a) for(int j=0;j<a;j++)
    
 #define ifor(a) for(int i=1;i<=a;i++)
    
 #define jfor(a) for(int j=1;j<=a;j++)
    
 #define mem(a,b) memset(a,b,sizeof(a))
    
 #define IN freopen("in.txt","r",stdin)
    
 #define OUT freopen("out.txt","w",stdout)
    
 #define IO do{\
    
     ios::sync_with_stdio(false);\
    
     cin.tie(0);\
    
     cout.tie(0);}while(0)
    
 using namespace std;
    
 typedef long long ll;
    
 const int maxn =  5*1e6+10;
    
 const int INF = 0x3f3f3f3f;
    
 const int inf = 0x3f;
    
 const double EPS = 1e-7;
    
 const double Pi = acos(-1);
    
 const int MOD = 1e9+7;
    
 bool a[maxn];
    
 bool use[maxn];
    
 int num[maxn];
    
 int main() {
    
     //IN;
    
     int k  = 0;
    
     int Max = -INF;
    
     int n,m;
    
     cin >> n >> m;
    
     fori(m+1)        //存下所有q*q+p*p的组合
    
     forj(i+1) {
    
     if(!a[i*i+j*j]) {
    
         num[k++] = i*i+j*j;
    
         a[i*i+j*j] = true;
    
         Max = max(Max,num[k-1]);
    
     }
    
     }
    
     sort(num,num+k);
    
     int d;
    
     bool res = false;
    
     for(int j=1; j*(n-1)<=Max; j++) {   //暴力求解即可
    
     for(int i=0; i<k; i++) { 
    
         int step = 1;
    
         d = num[i];
    
         while(a[d+j]&&step<n) {
    
             d += j;
    
             step ++;
    
         }
    
         if(step>=n){
    
             res = true;
    
             cout << num[i] <<" "<< j << endl;
    
         }
    
     }
    
     }
    
     if(!res)
    
     cout <<"NONE"<<endl;
    
     return 0;
    
 }