USACO ariprog 暴力枚举+剪枝

/*
ID:kevin_s1
PROG:ariprog
LANG:C++
*/

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
#include <cstdlib>
#include <list>
#include <cmath>

using namespace std;

//gobal variable====
int doubleSqure[999999];
int table[999999];
int _index;
int M,N;
int lim;

struct node{
int a;
int d;

};

vector<node> result;
//==================

//function==========
void init(){
memset(table,0,sizeof(table));
_index = 1;
for(int i = 0; i <= M; i++){
for(int j = 0; j <= M; j++){
int num = i * i + j * j;
if(table[num] == 0){
doubleSqure[_index++] = num;
table[num] = 1;
}
}
}
_index--;
}

void deal(int x){
int num = doubleSqure[x];
for(int i = x + 1; i <= _index - N + 2; i++){
if(doubleSqure[x] + (doubleSqure[i] - doubleSqure[x])*(N - 1) > lim)
break;

<span style="white-space:pre">		</span>//剪枝，没有这一步的话会第七组数据会超时
int d = doubleSqure[i] - num;
bool flag = true;
int count = doubleSqure[i];
for(int j = 3; j <= N; j++){
count += d;
if(table[count] == 0)
flag = false;
}
if(flag){
node no;
no.a = num;
no.d = d;
result.push_back(no);
}
}
}

bool cmp(const node& n1, const node& n2){
if(n1.d == n2.d)
return n1.a < n2.a;
else
return n1.d < n2.d;
}

//==================

int main(){
freopen("ariprog.in","r",stdin);
freopen("ariprog.out","w",stdout);
cin>>N>>M;
init();
sort(doubleSqure, doubleSqure + _index);
lim = doubleSqure[_index];

for(int i = 1; i <= _index - N + 1; i++){
deal(i);
}
sort(result.begin(), result.end(), cmp);
vector<node>::iterator iter;
if(result.size() == 0)
cout<<"NONE"<<endl;
else{
for(iter = result.begin(); iter != result.end(); iter++){
cout<<iter->a<<" "<<iter->d<<endl;
}
}
return 0;
}