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**Lists in Python:**

Lists are one of Python’s most commonly used built-in data structures. You can make a list by putting all of the elements inside square brackets[ ] and separating them with commas. Lists can include any type of object, making them extremely useful and adaptable.

Given a list/array, the task is to find the minimum index of the repeating element in the given list in Python.

**Examples:**

**Example1:**

**Input:**

given list = [8, 12, 38, 7, 1, 9, 19, 11, 45, 62, 57, 18, 12, 32, 45, 7, 1]

**Output:**

The minimum index of the repeating element of the given list [8, 12, 38, 7, 1, 9, 19, 11, 45, 62, 57, 18, 12, 32, 45, 7, 1] : 1

**Example2:**

**Input:**

given list =[7, 86, 23, 96, 11, 23, 45, 78, 96, 23, 79, 123, 456, 789]

**Output:**

The minimum index of the repeating element of the given list [7, 86, 23, 96, 11, 23, 45, 78, 96, 23, 79, 123, 456, 789] : 2

## Program to Find the Minimum Index of a Repeating Element in an Array/List in Python

Below is the full approach for finding the minimum index of the repeating element in the given list in Python

- Using Hashing with Counter() function(Static Input)
- Using Hashing with Counter() function(User Input)

### 1)Using Hashing with Counter() function(Static Input)

**Counter() function:**

The Counter class is a subset of the object data-set offered by Python3’s collections module. The Collections module provides the user with specialized container datatypes, acting as an alternative to Python’s general-purpose built-ins such as dictionaries, lists, and tuples.

The counter is a subclass that counts hashable objects. When called, it constructs an iterable hash table implicitly.

**Approach:**

- Import the Counter function from the collections module.
- Give the list as static input and store it in a variable.
- Calculate the frequency of all the elements of the given list using the Counter() function and store it in a variable.
- Traverse the given list using For loop.
- Check if the element has a frequency greater than 1 using the if statement.
- If it has a frequency greater than 1, then print the iterator value of the loop(which is the minimum index of the repeating element)
- Break the loop using a break statement
- The Exit of the Program.

**Below is the implementation:**

# Import the Counter function from the collections module. from collections import Counter # Give the list as static input and store it in a variable. given_list = [8, 12, 38, 7, 1, 9, 19, 11, 45, 62, 57, 18, 12, 32, 45, 7, 1] # Calculate the frequency of all the elements of the given list # using the Counter() function and store it in a variable. elemeFreq = Counter(given_list) # Traverse the given list using For loop. for indeval in range(len(given_list)): # Check if the element has a frequency greater than 1 using the if statement. if(elemeFreq[given_list[indeval]] > 1): # If it has a frequency greater than 1, then print the iterator value of the loop # (which is the minimum index of the repeating element) print('The minimum index of the repeating element of the given list', given_list, ':\n', indeval) # Break the loop using the break statement break

**Output:**

The minimum index of the repeating element of the given list [8, 12, 38, 7, 1, 9, 19, 11, 45, 62, 57, 18, 12, 32, 45, 7, 1] : 1

Since we iterate only once the Time Complexity of the above approach is O(n).

### 2)Using Hashing with Counter() function(User Input)

**Approach:**

- Import the Counter function from the collections module.
- Give the list as user input using split(),int,map() and list() functions.
- Store it in a variable.
- Calculate the frequency of all the elements of the given list using the Counter() function and store it in a variable.
- Traverse the given list using For loop.
- Check if the element has a frequency greater than 1 using the if statement.
- If it has a frequency greater than 1, then print the iterator value of the loop(which is the minimum index of the repeating element)
- Break the loop using a break statement
- The Exit of the Program.

**Below is the implementation:**

# Import the Counter function from the collections module. from collections import Counter # Give the list as user input using split(),int,map() and list() functions. # Store it in a variable. given_list = list( map(int, input('Enter some random list elements separated by spaces = ').split())) # Calculate the frequency of all the elements of the given list # using the Counter() function and store it in a variable. elemeFreq = Counter(given_list) # Traverse the given list using For loop. for indeval in range(len(given_list)): # Check if the element has a frequency greater than 1 using the if statement. if(elemeFreq[given_list[indeval]] > 1): # If it has a frequency greater than 1, then print the iterator value of the loop # (which is the minimum index of the repeating element) print('The minimum index of the repeating element of the given list', given_list, ':\n', indeval) # Break the loop using break statement break

**Output:**

Enter some random list elements separated by spaces = 7 86 23 96 11 23 45 78 96 23 79 123 456 789 The minimum index of the repeating element of the given list [7, 86, 23, 96, 11, 23, 45, 78, 96, 23, 79, 123, 456, 789] : 2

Since we iterate only once the Time Complexity of the above approach is O(n).

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