Python Program to find the duplicate number on a given integer array

Python Conversations
#1

import collections
def is_duplicate(array):
d=collections.Counter(array)
for k,v in d.items():
if v>=2:
print(k," is duplicate")

is_duplicate([1,2,3,4,5,2,1])

#2

@A_Abhiram

Correct, keep it up.
Keep Practicing.