You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
64 lines
1.2 KiB
Java
64 lines
1.2 KiB
Java
import java.util.*;
|
|
|
|
public class MaxMatchingRandomized {
|
|
|
|
static final int MOD = 29989;
|
|
|
|
static int pow(int a, int b) {
|
|
int res = 1;
|
|
for (; b > 0; b >>= 1) {
|
|
if ((b & 1) != 0)
|
|
res = res * a % MOD;
|
|
a = a * a % MOD;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
static int rank(int[][] a) {
|
|
int r = 0;
|
|
int n = a.length;
|
|
for (int j = 0; j < n; j++) {
|
|
int k;
|
|
for (k = r; k < n && a[k][j] == 0; k++)
|
|
;
|
|
if (k == n)
|
|
continue;
|
|
|
|
int[] t = a[r];
|
|
a[r] = a[k];
|
|
a[k] = t;
|
|
|
|
int inv = pow(a[r][j], MOD - 2);
|
|
for (int i = j; i < n; i++)
|
|
a[r][i] = a[r][i] * inv % MOD;
|
|
|
|
for (int u = r + 1; u < n; u++)
|
|
for (int v = j + 1; v < n; v++)
|
|
a[u][v] = (a[u][v] - a[r][v] * a[u][j] % MOD + MOD) % MOD;
|
|
++r;
|
|
}
|
|
return r;
|
|
}
|
|
|
|
public static int maxMatching(boolean[][] d) {
|
|
int n = d.length;
|
|
int[][] a = new int[n][n];
|
|
Random rnd = new Random(1);
|
|
for (int i = 0; i < n; i++) {
|
|
for (int j = 0; j < i; j++) {
|
|
if (d[i][j]) {
|
|
a[i][j] = rnd.nextInt(MOD - 1) + 1;
|
|
a[j][i] = MOD - a[i][j];
|
|
}
|
|
}
|
|
}
|
|
return rank(a) / 2;
|
|
}
|
|
|
|
// Usage example
|
|
public static void main(String[] args) {
|
|
int res = maxMatching(new boolean[][] { { false, true }, { true, false } });
|
|
System.out.println(1 == res);
|
|
}
|
|
}
|