Merge pull request #143 from aadityasinha-dotcom/intersection-of-arrays

Intersection of two arrays

Author: SarthakKeshari

Arrays/1D Arrays/intersectionOfTwoArrays.java

@@ -0,0 +1,46 @@
+/*
+Given two arrays arr1 and arr2. We need to find the intersection of both the arrays and return the result as a list.
+*/
+
+import java.util.*;
+
+public class intersectionOfTwoArrays{
+    
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int n1 = sc.nextInt();
+        int[] arr1 = new int[n1];
+        int n2 = sc.nextInt();
+        int[] arr2 = new int[n2];
+        for(int i = 0; i < n1; i++){
+            arr1[i] = sc.nextInt();
+        }
+        for(int i = 0; i < n1; i++){
+            arr2[i] = sc.nextInt();
+        }
+        intersection(arr1, arr2, n1, n2);
+        sc.close();
+    }
+    
+    public static void intersection(int[] a,int[] b, int n, int m){
+        HashMap<Integer,Integer> map = new HashMap<>();     // created a hashmap which will store distinct elements with their frequencies
+        for(int i = 0; i < n; i++){
+            map.put(a[i],map.getOrDefault(a[i],0)+1);      // updating frequencies of each element
+        }
+        int[] arr = new int[100001];        // created an array which will store the elements which are present in both the arrays
+        Arrays.fill(arr,0);              
+        for(int i = 0; i < m; i++){
+            if(map.containsKey(b[i])){   // updating array which contains elements that are present in both the arrays
+                arr[b[i]] = 1;
+            }
+        }
+        ArrayList<Integer> al = new ArrayList<>();     // creating a list 
+        for(int i = 0; i < m; i++){
+            if(arr[b[i]]==1){                // checking if the element is present in both the arrays or not
+                al.add(b[i]);                // adding the elements to the list
+            }
+        }
+        System.out.println(al);
+    }
+
+}