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Cleanup BoyerMoore #4951

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Merged
merged 14 commits into from
Oct 31, 2023
Merged

Cleanup BoyerMoore #4951

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225a49e
modify code to make use of java Optional class
prathameshpowar1910 Oct 31, 2023
353125d
revert changes
prathameshpowar1910 Oct 31, 2023
0527c59
add java.util.Optional<Integer>
prathameshpowar1910 Oct 31, 2023
286c042
add java.util.Optional
prathameshpowar1910 Oct 31, 2023
fe687c3
refactors: make `findmajor` return `optional`
vil02 Oct 31, 2023
59bbeb1
refactors: make method name findMajor and split it
prathameshpowar1910 Oct 31, 2023
199207d
refactors: change method name in tests
prathameshpowar1910 Oct 31, 2023
1c529e3
Apply suggestions from code review
prathameshpowar1910 Oct 31, 2023
8d17984
change back to int
prathameshpowar1910 Oct 31, 2023
33dd9ec
fix: swap arguments
vil02 Oct 31, 2023
448f568
tests: add some test cases
vil02 Oct 31, 2023
becbb02
refactor: add `isMajority` and avoid rounding
vil02 Oct 31, 2023
4864fc5
style: use `var`
vil02 Oct 31, 2023
6457289
style: swap arguments of `countOccurrences`
vil02 Oct 31, 2023
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modify code to make use of java Optional class
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@prathameshpowar1910
prathameshpowar1910 committed Oct 31, 2023
commit 225a49e7a23f374673fd6759ba0e9de3b38f2a3f
43 changes: 31 additions & 12 deletions src/main/java/com/thealgorithms/others/BoyerMoore.java
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Original file line number Diff line number Diff line change
Expand Up @@ -5,35 +5,54 @@
https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_majority_vote_algorithm
*/
package com.thealgorithms.others;
import java.util.Optional;

public final class BoyerMoore {
private BoyerMoore() {
}

public static int findmajor(final int[] a) {
private static Optional<Integer> findCandidate(final int[] a) {
int count = 0;
int cand = -1;
for (final var k : a) {
int candidate = -1;
for (final int k : a) {
if (count == 0) {
cand = k;
candidate = k;
count = 1;
} else {
if (k == cand) {
if (k == candidate) {
count++;
} else {
count--;
}
}
}
count = 0;
for (final var j : a) {
if (j == cand) {
return Optional.of(candidate);
}


public static Optional<Integer> findmajor(final int[] a) {
Optional<Integer> candidate = findCandidate(a);

if (candidate.isPresent() && isMajority(candidate.get(), a)) {
return candidate;
} else {
return Optional.empty();
}
}

private static int calculateOccurrences(final int candidate, final int[] a) {
int count = 0;
for (final int j : a) {
if (j == candidate) {
count++;
}
}
if (count > (a.length / 2)) {
return cand;
}
return -1;
return count;
}

private static boolean isMajority(final int candidate, final int[] a) {
int count = calculateOccurrences(candidate, a);
return count > (a.length / 2);
}

}