codeforces736D. Permutations(线性代数)

#include<cstdio>
#include<bitset>
#include<iostream>
using namespace std;
const int MAXN = 2001;
inline int read() {
    char c = getchar(); int x = 0, f = 1;
    while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}
    while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
    return x * f;
}
int N, M;
bitset<MAXN * 2 + 10> b[MAXN];
int x[500001], y[500001];
int main() {
    N = read(); M = read();
    for(int i = 1; i <= N; i++) b[i][i + N] = 1;
    for(int i = 1; i <= M; i++) {
        x[i] = read(), y[i] = read();
        b[x[i]][y[i]] = 1; 
    }
    for(int i = 1, j; i <= N; i++) {
        for(j = i; j <= N; j++) if(b[j][i]) {swap(b[i], b[j]); break;}
        for(int k = 1; k <= N; k++)
            if(b[k][i] && (k != i)) b[k] ^= b[i];
    }
    for(int i = 1; i <= N; i++, puts("")) 
        for(int j = 1; j <= 2 * N; j++) 
            cout << b[i][j] << " ";
    return 0;
}
/*
3 7
1 1 
1 3
2 2
2 3
3 1
3 2
3 3
 
*/