杭电多校第二场 1005 hack it

题意： 构造一个n*n 的 01 矩阵， 0 < n < 2001,  矩阵需要满足没有一个子矩阵的4个角都是1，并且矩阵内1的个数至少有85000个。

题解：数论构造题

参考From

代码：

#include<bits/stdc++.h>
using namespace std;
#define Fopen freopen("_in.txt","r",stdin); freopen("_out.txt","w",stdout);
#define LL long long
#define ULL unsigned LL
#define fi first
#define se second
#define pb push_back
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define max3(a,b,c) max(a,max(b,c))
#define min3(a,b,c) min(a,min(b,c))
typedef pair<int,int> pll;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const LL mod =  (int)1e9+7;
int P = 47;
const int N = 3010;
int a[N][N];
int main(){
    int n, m;
    for(int i = 0; i < P; i++)
        for(int j = 0; j < P; j++)
            for(int k = 0; k < P; k++)
                a[i*P + j][k*P + (k*i+j)%P] = 1;
    puts("2000");
    for(int i = 0; i < 2000; i++){
        for(int j = 0; j < 2000; j++)
            printf("%d", a[i][j]);
        puts("");
    }
    return 0;
}