Java solution to Codility Distinct problem (Lesson 6 – Sorting) which scored 100%. The problem is to count the number of distinct values in an array. The strategy is to use a java.util.Set to store only distinct elements and then get the size of the set.
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import java.util.HashSet;
import java.util.Set;
public class Distinct {
public int solution(int[] A) {
if(A.length == 0) return 0;
Set aSet = new HashSet();
for(int i=0; i<A.length; i++) {
aSet.add(A[i]);
}
return aSet.size();
}
}
TestNG test cases for this problem which all passed:
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import org.testng.Assert;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
import com.codility.lesson06.sorting.Distinct;
public class DistinctTests {
private Distinct solution;
@BeforeTest
public void setUp() {
solution = new Distinct();
}
@DataProvider(name = "test1")
public Object [][] createData1() {
return new Object [][] {
new Object [] { new int [] { 2, 1, 1, 2, 3, 1 }, 3 }, //1, 2, 3
new Object [] { new int [] { -3, 1, -100, -2, -2, 5, 6 }, 6 }, //-100, -3, -2, 1, 5, 6
new Object [] { new int [] { -3, 1, -100}, 3}, //-100, -3, 1
new Object [] { new int [] { 0, 0, 0, 0}, 1}, //0
new Object [] { new int [] { 0, -1, 0, -1}, 2}, //-1, 0
new Object [] { new int [] { 10 }, 1 }, //10
new Object [] { new int [] { }, 0 },
};
}
@Test(dataProvider = "test1")
public void verifySolution(int[] pA, int pExpected) {
Assert.assertEquals(solution.solution(pA), pExpected);
}
}