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：

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define Fopen freopen("_in.txt","r",stdin); freopen("_out.txt","w",stdout);
 4 #define LL long long
 5 #define ULL unsigned LL
 6 #define fi first
 7 #define se second
 8 #define pb push_back
 9 #define lson l,m,rt<<1
10 #define rson m+1,r,rt<<1|1
11 #define max3(a,b,c) max(a,max(b,c))
12 #define min3(a,b,c) min(a,min(b,c))
13 typedef pair<int,int> pll;
14 const int inf = 0x3f3f3f3f;
15 const LL INF = 0x3f3f3f3f3f3f3f3f;
16 const LL mod =  (int)1e9+7;
17 int P = 47;
18 const int N = 3010;
19 int a[N][N];
20 int main(){
21     int n, m;
22     for(int i = 0; i < P; i++)
23         for(int j = 0; j < P; j++)
24             for(int k = 0; k < P; k++)
25                 a[i*P + j][k*P + (k*i+j)%P] = 1;
26     puts("2000");
27     for(int i = 0; i < 2000; i++){
28         for(int j = 0; j < 2000; j++)
29             printf("%d", a[i][j]);
30         puts("");
31     }
32     return 0;
33 }

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