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ApplyPermutation.java
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ApplyPermutation.java
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package epi;
import epi.test_framework.EpiTest;
import epi.test_framework.GenericTest;
import java.util.Collections;
import java.util.List;
public class ApplyPermutation {
public static void applyPermutation(List<Integer> perm, List<Integer> A) {
for (int i = 0; i < A.size(); ++i) {
// Check if the element at index i has not been moved by checking if
// perm.get(i) is nonnegative.
int next = i;
while (perm.get(next) >= 0) {
Collections.swap(A, i, perm.get(next));
int temp = perm.get(next);
// Subtracts perm.size() from an entry in perm to make it negative,
// which indicates the corresponding move has been performed.
perm.set(next, perm.get(next) - perm.size());
next = temp;
}
}
// Restore perm.
for (int i = 0; i < perm.size(); i++) {
perm.set(i, perm.get(i) + perm.size());
}
}
@EpiTest(testDataFile = "apply_permutation.tsv")
public static List<Integer> applyPermutationWrapper(List<Integer> perm,
List<Integer> A) {
applyPermutation(perm, A);
return A;
}
public static void main(String[] args) {
System.exit(
GenericTest
.runFromAnnotations(args, "ApplyPermutation.java",
new Object() {}.getClass().getEnclosingClass())
.ordinal());
}
}