# Triple Sum – Hackerrank Challenge – Java solution

```import java.util.Arrays;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class TripleSumHackerrank {

static long triplets(int[] a, int[] b, int[] c) {

long distinctTripletCount = 0;

int[] distinctA = removeDuplicates(a);
int[] distinctB = removeDuplicates(b);
int[] distinctC = removeDuplicates(c);

Arrays.sort(distinctA);
Arrays.sort(distinctB);
Arrays.sort(distinctC);

for (int q : distinctB) {
long c1 = getValidIndex(distinctA, q) + 1;
long c3 = getValidIndex(distinctC, q) + 1;
distinctTripletCount += c1 * c3;
}

return distinctTripletCount;

}

private static int[] removeDuplicates(int[] a) {
Set<Integer> set = new HashSet<>();
for (int item : a) {
}
int len = set.size();

int result[] = new int[len];
int i = 0;
for (int item : set) {
result[i++] = item;
}
return result;
}

static int getValidIndex(int[] distinctA, int key) {
int low = 0;
int high = distinctA.length - 1;
int count = -1;

while (low <= high) {
int mid = low + (high - low) / 2;
if (distinctA[mid] <= key) {
count = mid;
low = mid + 1;
} else
high = mid - 1;
}
return count;

}

public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int lena = sc.nextInt();
int lenb = sc.nextInt();
int lenc = sc.nextInt();

int a[] = new int[lena];
int b[] = new int[lenb];
int c[] = new int[lenc];

for (int i = 0; i < lena; i++) {
a[i] = sc.nextInt();
}
for (int i = 0; i < lenb; i++) {
b[i] = sc.nextInt();
}
for (int i = 0; i < lenc; i++) {
c[i] = sc.nextInt();
}

long result = triplets(a, b, c);
System.out.println(result);
sc.close();
}
}```