60 lines
1.4 KiB
Java
60 lines
1.4 KiB
Java
public class Determinant1 {
|
|
static long gcd(long a, long b) {
|
|
while (b != 0) {
|
|
long t = b;
|
|
b = a % b;
|
|
a = t;
|
|
}
|
|
return Math.abs(a);
|
|
}
|
|
|
|
public static long det(long[][] a) {
|
|
int n = a.length;
|
|
long div = 1;
|
|
long det = 1;
|
|
for (int i = 0; i < n; ++i) {
|
|
int k = i;
|
|
for (int j = i + 1; j < n; ++j) {
|
|
if (a[j][i] != 0) {
|
|
k = j;
|
|
break;
|
|
}
|
|
}
|
|
if (a[k][i] == 0)
|
|
return 0;
|
|
if (i != k) {
|
|
det = -det;
|
|
long[] t = a[i];
|
|
a[i] = a[k];
|
|
a[k] = t;
|
|
}
|
|
det *= a[i][i];
|
|
long gcd = gcd(det, div);
|
|
det /= gcd;
|
|
div /= gcd;
|
|
for (int j = i + 1; j < n; ++j)
|
|
if (j != i && a[j][i] != 0) {
|
|
for (int p = i + 1; p < n; ++p)
|
|
a[j][p] = a[j][p] * a[i][i] - a[i][p] * a[j][i];
|
|
// a[j][i] = 0;
|
|
if (i < n - 1)
|
|
div *= a[i][i];
|
|
gcd = gcd(det, div);
|
|
det /= gcd;
|
|
div /= gcd;
|
|
}
|
|
}
|
|
return det / div;
|
|
}
|
|
|
|
public static void main(String[] args) {
|
|
|
|
System.out.println(279 == det(new long[][] { { 2, 4, 3, 5, 4 }, { 5, 4, 0, 2, 4 }, { 0, 5, 5, 2, 3 },
|
|
{ 1, 0, 4, 3, 0 }, { 0, 5, 1, 4, 4 } }));
|
|
System.out.println(-5 == det(new long[][] { { 3, 2, 2 }, { 0, 0, 5 }, { 4, 3, 1 } }));
|
|
System.out.println(-4 == det(new long[][] { { 2, 2, 2 }, { 1, 2, 0 }, { 2, 2, 0 } }));
|
|
System.out.println(-2 == det(new long[][] { { 1, 2 }, { 3, 4 } }));
|
|
System.out.println(6 == det(new long[][] { { 2, 4 }, { 0, 3 } }));
|
|
}
|
|
}
|