Find the Duplicate Elements in the List – Python List Program

In this post we will learn about basic list program to print the elements which are duplicate .

Problem

Here is example of the problem  –

Input: [ 1,2,3,3,2,2,4,]

Output:  [ 2,3 ]

In this example we need to find the duplicate elements, here 2 and 3 are the duplicate elements.

Solutions

Basic approach to solve this problem is to traverse through whole list and compare each element with all the elements of the list multiple times. If we see the second occurrence of the element then we will print the element and break the inner loop.

Here is detailed program to illustrate –

Program  for Duplicate Element

s=[1,2,3,4,1,2,4]
n=0
nl=[]  # output list
while n<len(s):
  d=0
  while d<len(s):
    if s[n]==s[d] and n!=d :
      if s[n] not in nl:
        nl.append(s[n])
      break
    d=d+1
  n=n+1
print(nl)

Output :

[1,2,4]

To conclude this is the basic brute force method for finding the duplicate elements.

Tags : python program to find duplicate, duplicate element program, basic python program, list duplicate

Please  check out other python programs –

How Does Python 2 Compare String And Int?