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26 changes: 26 additions & 0 deletions src/searching/MajorityElement.java
Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
package searching;

/**
* LeetCode Problem 169: Majority Element
* Boyer-Moore Voting Algorithm
*/
public class MajorityElement {
public static int findMajority(int[] nums) {
int count = 0;
Integer candidate = null;

for (int num : nums) {
if (count == 0) {
candidate = num;
}
count += (num == candidate) ? 1 : -1;
}

return candidate;
}

public static void main(String[] args) {
int[] nums = {2, 2, 1, 1, 1, 2, 2};
System.out.println("Majority element: " + findMajority(nums));
}
}
26 changes: 26 additions & 0 deletions src/test/java/search/MajorityElementTest.java
Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
package search;

import searching.MajorityElement;
import org.junit.Test;
import static org.junit.Assert.assertEquals;

public class MajorityElementTest {

@Test
public void testMajorityElement1() {
int[] nums = {3, 3, 4, 2, 3, 3, 3};
assertEquals(3, MajorityElement.findMajority(nums));
}

@Test
public void testMajorityElement2() {
int[] nums = {2, 2, 1, 1, 2, 2};
assertEquals(2, MajorityElement.findMajority(nums));
}

@Test
public void testMajorityElementSingle() {
int[] nums = {1};
assertEquals(1, MajorityElement.findMajority(nums));
}
}
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