64 lines
1.2 KiB
Java
64 lines
1.2 KiB
Java
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import java.util.*;
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public class MaxMatchingRandomized {
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static final int MOD = 29989;
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static int pow(int a, int b) {
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int res = 1;
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for (; b > 0; b >>= 1) {
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if ((b & 1) != 0)
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res = res * a % MOD;
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a = a * a % MOD;
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}
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return res;
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}
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static int rank(int[][] a) {
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int r = 0;
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int n = a.length;
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for (int j = 0; j < n; j++) {
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int k;
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for (k = r; k < n && a[k][j] == 0; k++)
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;
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if (k == n)
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continue;
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int[] t = a[r];
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a[r] = a[k];
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a[k] = t;
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int inv = pow(a[r][j], MOD - 2);
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for (int i = j; i < n; i++)
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a[r][i] = a[r][i] * inv % MOD;
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for (int u = r + 1; u < n; u++)
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for (int v = j + 1; v < n; v++)
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a[u][v] = (a[u][v] - a[r][v] * a[u][j] % MOD + MOD) % MOD;
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++r;
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}
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return r;
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}
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public static int maxMatching(boolean[][] d) {
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int n = d.length;
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int[][] a = new int[n][n];
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Random rnd = new Random(1);
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for (int i = 0; i < n; i++) {
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for (int j = 0; j < i; j++) {
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if (d[i][j]) {
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a[i][j] = rnd.nextInt(MOD - 1) + 1;
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a[j][i] = MOD - a[i][j];
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}
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}
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}
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return rank(a) / 2;
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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 res = maxMatching(new boolean[][] { { false, true }, { true, false } });
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System.out.println(1 == res);
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}
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}
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