Help me in solving DSU11 problem

My issue

have some other doubt

My code

parent = []
size = []

def dsu_find(a):
    if parent[a] == a:
        return a
    parent[a] = dsu_find(parent[a])
    return parent[a]

def dsu_union(a, b):
    leader_a = dsu_find(a)
    leader_b = dsu_find(b)
    if leader_a != leader_b:
        if size[leader_b] < size[leader_a]:
            leader_a, leader_b = leader_b, leader_a
        parent[leader_b] = leader_a
        size[leader_b] += size[leader_a]

if __name__ == '__main__':
    #Write your code here

Learning course: Disjoint Set Union
Problem Link: Check if two elements are connected Practice Problem in Disjoint Set Union - CodeChef