ArrayIntersection.java

packagesection16_Hashmap;

importjava.util.Arrays;
importjava.util.HashMap;

publicclassArrayIntersection {

publicstaticvoidmain(String[] args) {

int[] arr1 = { 5, 1, 3, 4, 7 };
int[] arr2 = { 2, 4, 3, 5, 7, 10, 15 };

int[] intersection = intersectionArrays(arr1, arr2);

System.out.println(Arrays.toString(intersection));
 }

staticint[] intersectionArrays(int[] arr1, int[] arr2) {
HashMap<Integer, Integer> map = newHashMap<Integer, Integer>();

// constraints: all elements are unique in given individual array
for (inti = 0; i < arr1.length; i++) {
map.put(arr1[i], 1);
 }

intintersectCount = 0;

// this loop can be avoided using ArrayList
for (inti = 0; i < arr2.length; i++) {
if (map.containsKey(arr2[i]))
intersectCount++;
 }

int[] intersections = newint[intersectCount];
intindex = 0;
for (inti = 0; i < arr2.length; i++) {
if (map.containsKey(arr2[i])) {
intersections[index] = arr2[i];
index++;
 }
 }

returnintersections;
 }
}