Union and Intersection of Two Sorted Arrays

Union and Intersection of Two Sorted arrays

Given two sorted arrays of any length, Find Union and Intersection of given arrays.

Lets understand the problem statement graphically and it will be more clear,

Algorithm


Take 2 pointers i and j,
  1. Pointer i pointing to 1st index of Array 1 & Pointer j pointing to 1st index of Array 2
  2. If arr1[i] == arr2[j], it means, element is common in both array, So write it to intersection string and one copy to union string as well and increment both pointer i and j.
  3. If arr1[i] < arr2[j], it means, arr[i] is smaller, So write arr1[i] to union string and increment pointer i.
  4. If arr1[i] > arr2[j], it means, arr[j] is smaller, So write arr2[j] to union string and increment pointer j.
  5. If the length of arr1 and arr2 is different, then comparison works till length of both array is same. So after comparison loop breaks, we need to check which array is larger and copy that array element to union string.

Union and Intersection of Two Sorted arrays Java Program


public class UnionAndIntersectionOfTtwoSortedArrays {
 public static void main(String[] args) {
  int arr1[] = {10, 15, 22, 80};
  int arr2[] = {5, 10, 11, 22, 70, 90};
  
  unionAndIntersectionOfTtwoSortedArrays(arr1, arr2);
 }
 
 private static void unionAndIntersectionOfTtwoSortedArrays(int[] arr1, int[] arr2){
  String union = "";
  String intersection = "";
  
  int i=0; int j=0;
  while(i < arr1.length && j < arr2.length) {
   if(arr1[i] == arr2[j]){
    union += arr1[i] + " ";
    intersection += arr1[i] + " ";
    
    i++; j++;
   }else if(arr1[i] < arr2[j]){
    union += arr1[i] + " ";
    i++;
   }else{
    union += arr2[j] + " ";
    j++;
   }
  }
  
  while(i < arr1.length){
   union += arr1[i];
  }
   
  while(j < arr2.length) {
   union += arr2[j];
  }
  
  System.out.println("union :"+union);
  System.out.println("intersection :"+intersection);
 }
}

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Enjoy !!!! 

If you find any issue in post or face any error while implementing, Please comment.

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