[python] Union and Intersection of two sorted arrays

Given two sorted arrays, find their union and intersection.

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}

# 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)

# Python3 program to find union of two
# sorted arrays (Handling Duplicates)
def UnionArray(arr1, arr2):
     
    # Taking max element present in either array
    m = arr1[-1]
    n = arr2[-1]
    ans = 0
         
    if m > n:
        ans = m
    else:
        ans = n
         
    # Finding elements from 1st array
    # (non duplicates only). Using
    # another array for storing union
    # elements of both arrays
    # Assuming max element present
    # in array is not more than 10 ^ 7
    newtable = [0] * (ans + 1)
         
    # First element is always
    # present in final answer
    print(arr1[0], end = " ")
         
    # Incrementing the First element's count
    # in it's corresponding index in newtable
    newtable[arr1[0]] += 1
         
    # Starting traversing the first
    # array from 1st index till last
    for i in range(1, len(arr1)):
         
        # Checking whether current element
        # is not equal to it's previous element
        if arr1[i] != arr1[i - 1]:
             
            print(arr1[i], end = " ")
            newtable[arr1[i]] += 1
             
    # Finding only non common
    # elements from 2nd array        
    for j in range(0, len(arr2)):
         
        # By checking whether it's already
        # present in newtable or not
        if newtable[arr2[j]] == 0:
             
            print(arr2[j], end = " ")
            newtable[arr2[j]] += 1
     
# Driver Code
if __name__ == "__main__":
     
    arr1 = [1, 2, 2, 2, 3]
    arr2 = [2, 3, 4, 5]
         
    UnionArray(arr1, arr2)

# Python3 program to find Intersection of two
# Sorted Arrays (Handling Duplicates)
def IntersectionArray(a, b, n, m):
    '''
    :param a: given sorted array a
    :param n: size of sorted array a
    :param b: given sorted array b
    :param m: size of sorted array b
    :return: array of intersection of two array or -1
    '''
 
    Intersection = []
    i = j = 0
     
    while i < n and j < m:
        if a[i] == b[j]:
 
            # If duplicate already present in Intersection list
            if len(Intersection) > 0 and Intersection[-1] == a[i]:
                i+= 1
                j+= 1
 
            # If no duplicate is present in Intersection list
            else:
                Intersection.append(a[i])
                i+= 1
                j+= 1
        elif a[i] < b[j]:
            i+= 1
        else:
            j+= 1
             
    if not len(Intersection):
        return [-1]
    return Intersection
 
# Driver Code
if __name__ == "__main__":
 
    arr1 = [1, 2, 2, 3, 4]
    arr2 = [2, 2, 4, 6, 7, 8]
     
    l = IntersectionArray(arr1, arr2, len(arr1), len(arr2))
    print(*l)