Intersection and Union of Arrays

Problem Statement: 
         Find the Intersection and Union of Arrays

Solution:
 Below we will find solution of problem in O(n) and assuming the arrays are already sorted.

Full Source Code : LINK

Intersection Logic: 
1. If 1st array element is smaller , increment its index
2. If 2nd array element is smaller , increment its index.
3. If equal, print either , and increment both.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

/** * Intersection of Arrays */ public void intersection() { int i=0; int j=0; while(i < arr1.length && j < arr2.length) { if(arr1[i] < arr2[j]) i++; else if(arr1[i] > arr2[j]) j++; else { System.out.print(arr1[i++] + "\t"); j++; } } }

Union Logic:
1. If element of 1st array is smaller print it, and increment index. 
2. If element of 2st array is smaller print it, and increment index.
3. If both are equal , print arr1 element and increment both indexes of both arrays
4. Print remaining array of the larger array.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

/** * Union Of arrays */ public void union() { int i=0,j=0; while(i < arr1.length && j < arr2.length) { if(arr1[i] < arr2[j]) System.out.print(arr1[i++]); else if(arr1[i] > arr2[j]) System.out.print(arr2[j++]); else { System.out.print(arr1[i++]); j++; } System.out.print("\t"); } if(arr2.length > arr1.length) for(;j<arr2.length;System.out.println(arr2[j]),j++); else if(arr2.length < arr1.length) for( ; i<arr1.length;System.out.println(arr1[i]),i++); }

Please comment and post your suggestions.
Happy Coding!! :)