"Gaussian elimination" "Xor Equations" "Bitset" bzoj1923 [Sdoi2010] alien thousand-legged worm

The number of solutions for the Xor equation Group is determined:

--Mo Tao--"Gaussian elimination solution of the Xor Equation Group"

Use the number of equations to determine: When the first unknown is eliminated, it is recorded that the nearest I-bit coefficient of the first equation is not the 0の equation, which Max uses the number of equations.

Use Bitset acceleration.

#include <cstdio> #include <cmath> #include <algorithm> #include <bitset>using namespace std;# Define N 1001#define M 2001int n,m,use;char s[n];bool a[m][n+1],x[n],b[m];bitset<n+1>b[m];bool Guass_jordan () { for (int i=1;i<=m;++i) for  (int j=1;j<=n;++j)    b[i][j]=a[i][j];for (int i=1;i<=m;++i)  b[i][n+1]= b[i];for (int i=1;i<=n;++i)  {  int j=i;  for (; j<=m;++j)    if (B[j][i]) break      ;  if (j==m+1)  return 0;  Use=max (use,j);  Swap (b[i],b[j]);  for (J=1;J<=M;++J)    if (I!=j&&b[j][i])      b[j]^=b[i];  } for (int i=1;i<=m;++i) X[i]=b[i][n+1];return 1;} int main () {scanf ("%d%d", &n,&m), for (int i=1;i<=m;++i)  {  scanf ("%s%d", S,&b[i]);  for (int j=0;j<n;++j)    a[i][j+1]=s[j]-' 0 ';  } if (!guass_jordan ())  puts ("cannot determine"), else  {  printf ("%d\n", use);  for (int i=1;i<=n;++i)    puts (X[i]? "? y7m# ":" Earth ");  } return 0;}

"Gaussian elimination" "Xor Equations" "Bitset" bzoj1923 [Sdoi2010] alien thousand-legged worm