66 lines
1.4 KiB
Java
66 lines
1.4 KiB
Java
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public class Matrix {
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public static int[][] matrixAdd(int[][] a, int[][] b) {
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int n = a.length;
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int m = a[0].length;
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int[][] res = new int[n][m];
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for (int i = 0; i < n; i++) {
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for (int j = 0; j < m; j++) {
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res[i][j] = a[i][j] + b[i][j];
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}
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}
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return res;
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}
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public static int[][] matrixMul(int[][] a, int[][] b) {
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int n = a.length;
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int m = a[0].length;
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int k = b[0].length;
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int[][] res = new int[n][k];
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for (int i = 0; i < n; i++) {
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for (int j = 0; j < k; j++) {
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for (int p = 0; p < m; p++) {
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res[i][j] = res[i][j] + a[i][p] * b[p][j];
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}
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}
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}
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return res;
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}
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public static int[][] matrixPow(int[][] a, int p) {
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if (p == 0) {
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return matrixUnit(a.length);
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} else if (p % 2 == 0) {
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return matrixPow(matrixMul(a, a), p / 2);
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} else {
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return matrixMul(a, matrixPow(a, p - 1));
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}
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}
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public static int[][] matrixPowSum(int[][] a, int p) {
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int n = a.length;
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if (p == 0) {
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return new int[n][n];
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}
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if (p % 2 == 0) {
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return matrixMul(matrixPowSum(a, p / 2), matrixAdd(matrixUnit(n), matrixPow(a, p / 2)));
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} else {
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return matrixAdd(a, matrixMul(matrixPowSum(a, p - 1), a));
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}
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}
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public static int[][] matrixUnit(int n) {
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int[][] res = new int[n][n];
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for (int i = 0; i < n; ++i) {
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res[i][i] = 1;
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}
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return res;
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}
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// Usage example
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public static void main(String[] args) {
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int[][] a = { { 1, 2 }, { 3, 4 } };
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int[][] b = matrixUnit(2);
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int[][] c = matrixMul(a, b);
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}
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}
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