# Union of arrays arr1[] and arr2[] using Python

Given two sorted arrays, find their union and intersection.
Example:

Input : arr1[] = {1, 3, 4, 5, 7} arr2[] = {2, 3, 5, 6} Output : Union : {1, 2, 3, 4, 5, 6, 7} Intersection : {3, 5} Input : arr1[] = {2, 5, 6} arr2[] = {4, 6, 8, 10} Output : Union : {2, 4, 5, 6, 8, 10} Intersection : {6}

Union of arrays arr1[] and arr2[]

To find union of two sorted arrays, follow the following merge procedure :

1. Use two index variables i and j, initial values i = 0, j = 0
2. If arr1[i] is smaller than arr2[j] then print arr1[i] and increment i.
3. If arr1[i] is greater than arr2[j] then print arr2[j] and increment j.
4. If both are same then print any of them and increment both i and j.
5. Print remaining elements of the larger array.

Below is the implementation of the above approach

`# Python program to find union of`

`# two sorted arrays`

`# Function prints union of arr1[] and arr2[]`

`# m is the number of elements in arr1[]`

`# n is the number of elements in arr2[]`

`def` `printUnion(arr1, arr2, m, n):`

` ` `i, j ` `=` `0` `, ` `0`

` ` `while` `i < m ` `and` `j < n:`

` ` `if` `arr1[i] < arr2[j]:`

` ` `print` `(arr1[i])`

` ` `i ` `+` `=` `1`

` ` `elif` `arr2[j] < arr1[i]:`

` ` `print` `(arr2[j])`

` ` `j` `+` `=` `1`

` ` `else` `:`

` ` `print` `(arr2[j])`

` ` `j ` `+` `=` `1`

` ` `i ` `+` `=` `1`

` ` `# Print remaining elements of the larger array`

` ` `while` `i < m:`

` ` `print` `(arr1[i])`

` ` `i ` `+` `=` `1`

` ` `while` `j < n:`

` ` `print` `(arr2[j])`

` ` `j ` `+` `=` `1`

`# Driver program to test above function`

`arr1 ` `=` `[` `1` `, ` `2` `, ` `4` `, ` `5` `, ` `6` `]`

`arr2 ` `=` `[` `2` `, ` `3` `, ` `5` `, ` `7` `]`

`m ` `=` `len` `(arr1)`

`n ` `=` `len` `(arr2)`

`printUnion(arr1, arr2, m, n)`

Output:

1 2 3 4 5 6 7

Time Complexity : O(m + n)