Don"t understand a part of quick union code

Python
1

i am study the quick union in coursera and implement it in python.
but a part of code can’t understand.is tree data structure need to learn first?

id=[i for i in range(10)]
def root(i):
    while i!=id[i]: #this part can not understand,how this declare the root and the loop works
        print(i)
        i=id[i]
    return i    

def union(p,q):
    i=root(p)
    j=root(q)
    id[i]=j

def check(p,q):
    return root(p)==root(q)
union(2,3)
print(root(2))

i hope someone help me to understand this topic.thank you in advance.

3

Change the parameter ‘i’ in function root to another letter may help you understand it. And some prints will make you see what’s going on.

id=[i for i in range(10)]  # id=[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
def root(j): 
    print("Now j is %s, id[j] is %s" %(j, id[j]))
    while j != id[j]:
        print(" j != id[j]" ) # when this line is printed out, you will know that the while condition is true.
        print(j) 
        j=id[j] 
    print("j is printed as %s" %j ) # change return to print, it's easier to see the final result.
    print()

for k in range(len(id)):
    root(k)

Run the code, you will get a result like this:

Now j is 0, id[j] is 0
j is printed as 0

Now j is 1, id[j] is 1
j is printed as 1

Now j is 2, id[j] is 2
j is printed as 2

Now j is 3, id[j] is 3
j is printed as 3

Now j is 4, id[j] is 4
j is printed as 4

Now j is 5, id[j] is 5
j is printed as 5

Now j is 6, id[j] is 6
j is printed as 6

Now j is 7, id[j] is 7
j is printed as 7

Now j is 8, id[j] is 8
j is printed as 8

Now j is 9, id[j] is 9
j is printed as 9