My function doesn't work(works but gives wrong answer)

Question

I m trying to have this result: [5,4,8]

but I m getting this: []

listA = [4,1,8,4,5]
listB = [5,6,1,8,4,5]

class Solution(object):
    
    def getIntersectionNode(listA,listB):
        de=[]
        for i in range(-1,-len(listB)): 
            for j in range(-1,-len(listB)):
                
                if listA[i] == listB[i]:de.append(listA[-1])
                
                elif listA[-1] != listB[-1]: print("null")  
                                          
                
        return de

What is wrong with this code?

Why did you use negative numbers in `range`? Presumably those are empty ranges. — mkrieger1, Mar 04 '21 at 20:24
You shouldn't get any result because you never create an instance of the class. — Matthias, Mar 04 '21 at 20:24
@MA To start from the end use `range(len(listB) - 1, -1, -1)` — Roy Cohen, Mar 04 '21 at 20:25
Does this answer your question? [Traverse a list in reverse order in Python](https://stackoverflow.com/questions/529424/traverse-a-list-in-reverse-order-in-python) — mkrieger1, Mar 04 '21 at 20:26
https://stackoverflow.com/questions/3697432/how-to-find-list-intersection — chess_lover_6, Mar 04 '21 at 20:27
@MA, you don't need to start from the end. The problem you try to solve is the problem #160 from leetcode, https://leetcode.com/problems/intersection-of-two-linked-lists/. You asked to find the intersection of **linked** lists, not built-in python lists — Konstantin, Mar 04 '21 at 20:30
range(-1,len(listA), - 1) range(-1,len(listB), - 1)this is the answer thanks — M A, Mar 04 '21 at 20:52

score 0 · Answer 1 · answered Mar 04 '21 at 20:28

0

If you don't need to worry about duplicates:

listA = [4,1,8,4,5]
listB = [5,6,1,8,4,5]

class Solution(object):
    
    def getIntersectionNode(listA,listB):
        de=list(set(listA) & set(listB))
             
        return de   
print(Solution.getIntersectionNode(listA,listB))

answered Mar 04 '21 at 20:28

chess_lover_6

632
8
22

it has to start from end of the list and must stop when it differs(in this case it is just 5,4,8) – M A Mar 04 '21 at 20:30

score 0 · Answer 2 · answered Mar 04 '21 at 20:29

0

The intersection is not [8, 1, 4, 5]?

If what you want is the intersection, you could use sets to achieve that easily:

list(set(listA).intersection(set(listB)))

answered Mar 04 '21 at 20:29

Martín Muñoz del Río

1,958
11
14

My function doesn't work(works but gives wrong answer)

2 Answers2