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