# Python program to count Even and Odd numbers in a List

Last Updated : 22 Apr, 2023

Given a list of numbers, write a Python program to count Even and Odd numbers in a List.

Example:

Input: list1 = [2, 7, 5, 64, 14]
Output: Even = 3, odd = 2

Input: list2 = [12, 14, 95, 3]
Output: Even = 2, odd = 2

Example 1:

Count Even and Odd numbers from the given list using for loop Iterate each element in the list using for loop and check if num % 2 == 0, the condition to check even numbers. If the condition satisfies, then increase the even count else increase odd count.

## Python3

 `# Python program to count Even` `# and Odd numbers in a List`   `# list of numbers` `list1 ``=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``1``]`   `even_count, odd_count ``=` `0``, ``0`   `# iterating each number in list` `for` `num ``in` `list1:`   `    ``# checking condition` `    ``if` `num ``%` `2` `=``=` `0``:` `        ``even_count ``+``=` `1`   `    ``else``:` `        ``odd_count ``+``=` `1`   `print``(``"Even numbers in the list: "``, even_count)` `print``(``"Odd numbers in the list: "``, odd_count)`

Output:

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(N), Here N is the number of elements in the list.
Auxiliary Space: O(1), As constant extra space is used.

Example 2: Using while loop

## Python3

 `# Python program to count Even and Odd numbers in a List`   `# list of numbers` `list1 ``=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``11``]`   `even_count, odd_count ``=` `0``, ``0` `num ``=` `0`   `# using while loop     ` `while``(num < ``len``(list1)):` `    `  `    ``# checking condition` `    ``if` `list1[num] ``%` `2` `=``=` `0``:` `        ``even_count ``+``=` `1` `    ``else``:` `        ``odd_count ``+``=` `1` `    `  `    ``# increment num ` `    ``num ``+``=` `1` `    `  `print``(``"Even numbers in the list: "``, even_count)` `print``(``"Odd numbers in the list: "``, odd_count)`

Output:

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(N), Here N is the number of elements in the list.
Auxiliary Space: O(1), As constant extra space is used.

Example 3: Using Python Lambda Expressions

## Python3

 `# list of numbers` `list1 ``=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``11``]`   `odd_count ``=` `len``(``list``(``filter``(``lambda` `x: (x``%``2` `!``=` `0``) , list1)))`   `# we can also do len(list1) - odd_count` `even_count ``=` `len``(``list``(``filter``(``lambda` `x: (x``%``2` `=``=` `0``) , list1)))`   `print``(``"Even numbers in the list: "``, even_count)` `print``(``"Odd numbers in the list: "``, odd_count)`

Output:

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(n)
Space Complexity: O(1)

Example 4: Using List Comprehension

## Python3

 `# Python program to print odd Numbers in a List`   `# list of numbers` `list1 ``=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``11``]`   `only_odd ``=` `[num ``for` `num ``in` `list1 ``if` `num ``%` `2` `=``=` `1``]` `odd_count ``=` `len``(only_odd)`   `print``(``"Even numbers in the list: "``, ``len``(list1) ``-` `odd_count)` `print``(``"Odd numbers in the list: "``, odd_count)`

Output:

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(N), Here N is the number of elements in the list.
Auxiliary Space: O(1), As constant extra space is used.

Example 5: Using Recursion

## Python3

 `# Python program to count Even` `# and Odd numbers in a List` `# using recursion` `even_count ``=` `0`  `# even counter` `i ``=` `0`  `# index, so that we can check if list[i] is even or odd` `odd_count ``=` `0`  `# odd counter`     `def` `evenoddcount(lst):` `    ``# defining local counters as global variable` `    ``global` `even_count` `    ``global` `odd_count` `    ``global` `i` `    ``if` `lst[i] ``%` `2` `=``=` `0``:  ``# check if number is even` `        ``even_count ``+``=` `1` `    ``else``:  ``# if number is odd` `        ``odd_count ``+``=` `1` `    ``if` `i ``in` `range``(``len``(lst)``-``1``):` `        ``i ``+``=` `1`  `# increment i` `        ``evenoddcount(lst)  ``# calling fonction recursively` `    ``else``:` `        ``print``(``"Even numbers in the list: "``, even_count)` `        ``print``(``"Odd numbers in the list: "``, odd_count)`     `list1 ``=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``1``]` `evenoddcount(list1)`

Output

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(N), Here N is the number of elements in the list.
Auxiliary Space: O(1), As constant extra space is used.

Example 6: Using Bitwise XOR operator

The idea is to check whether the last bit of the number is set or not. If the last bit is set then the number is odd, otherwise even. As we know bitwise XOR Operation of the Number by 1 increments the value of the number by 1 if the number is even otherwise it decrements the value of the number by 1 if the value is odd.

CHECK IF NUMBER IS EVEN OR ODD USING XOR OPERATOR

## Python3

 `# Python program to count Even` `# and Odd numbers in a List` `# using Bitwise XOR`   `# list of numbers` `list1 ``=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``1``]`   `even_count, odd_count ``=` `0``, ``0` `for` `num ``in` `list1:`   `    ``# checking condition` `    ``if` `num ^ ``1` `=``=` `num ``+` `1``:` `        ``even_count ``+``=` `1`   `    ``else``:` `        ``odd_count ``+``=` `1`   `print``(``"Even numbers in the list: "``, even_count)` `print``(``"Odd numbers in the list: "``, odd_count)` `# This code is contributed by Shivesh Kumar Dwivedi`

Output

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(N), Here N is the number of elements in the list.
Auxiliary Space: O(1), As constant extra space is used.

Example 7: Using Bitwise AND operator

The idea is to check whether the last bit of the number is set or not. If the last bit is set then the number is odd, otherwise even.
As we know bitwise AND Operation of the Number by 1 will be 1, If it is odd because the last bit will be already set. Otherwise, it will give 0 as output.

## Python3

 `# Python program to count Even` `# and Odd numbers in a List` `# using Bitwise AND`   `# list of numbers` `list1 ``=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``1``]`   `even_count, odd_count ``=` `0``, ``0` `for` `num ``in` `list1:`   `    ``# checking condition` `    ``if` `not` `num & ``1``:` `        ``even_count ``+``=` `1`   `    ``else``:` `        ``odd_count ``+``=` `1`   `print``(``"Even numbers in the list: "``, even_count)` `print``(``"Odd numbers in the list: "``, odd_count)`

Output

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(N), Here N is the number of elements in the list.
Auxiliary Space: O(1), As constant extra space is used.

Example 8: Using Bitwise OR operator

The idea is to check whether the last bit of the number is set or not. If the last bit is set then the number is odd, otherwise even. As we know bitwise OR Operation of the Number by 1 increment the value of the number by 1 if the number is even otherwise it will remain unchanged. So, if after OR operation of number with 1 gives a result which is greater than the number then it is even and we will return true otherwise it is odd and we will return false.

## Python3

 `# Python program to count Even` `# and Odd numbers in a List` `# using Bitwise OR`   `# list of numbers` `list1 ``=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``1``]`   `even_count, odd_count ``=` `0``, ``0` `for` `num ``in` `list1:` `      `  `    ``# checking condition` `    ``if` `num | ``1` `> num:` `        ``even_count ``+``=` `1` `  `  `    ``else``:` `        ``odd_count ``+``=` `1` `          `  `print``(``"Even numbers in the list: "``, even_count)` `print``(``"Odd numbers in the list: "``, odd_count)` `# This code is contributed by Shivesh Kumar Dwivedi`

Output

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(N), Here N is the number of elements in the list.
Auxiliary Space: O(1), As constant extra space is used.

## Python3

 `lst ``=` `[``12``, ``14``, ``95``, ``3``];c``=``0``;c1``=``0` `for` `i,a ``in` `enumerate``(lst):` `    ``if` `a``%``2``=``=``0``:` `        ``c``+``=``1` `    ``else``: ` `        ``c1``+``=``1` `    `  `print``(``"even number count"``,c,``"odd number count"``,c1)`

Output

`even number count 2 odd number count 2`

Time Complexity: O(N), Here N is the number of elements in the list.
Auxiliary Space: O(1), As constant extra space is used.

## Python

 `# Python program to Print Positive Numbers in a List` `import` `numpy as np`   `# list of numbers` `List` `=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``11``]`   `# using numpy Array` `list1 ``=` `np.array(``List``)` `Even_list ``=` `list1[list1 ``%` `2` `=``=` `0``]`   `print``(``"Even numbers in the list: "``, ``len``(Even_list))` `print``(``"Odd numbers in the list: "``, ``len``(list1)``-``len``(Even_list))`

Output:

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(N), Here N is the number of elements in the list.
Auxiliary Space: O(1), As constant extra space is used.

Method: Using Numpy.where() function :

## note: install numpy module using command “pip install numpy”

Algorithm:

Convert the given list to a numpy array.
Use numpy.where() function to find the indices of even and odd numbers in the array.
Count the number of indices using the len() function.
Print the counts.

Here’s the Python program to count Even and Odd numbers in a List using numpy.where() function:

## Python3

 `import` `numpy as np`   `# list of numbers` `list1 ``=` `[``2``, ``7``, ``5``, ``64``, ``14``]`   `# create numpy array from list` `arr ``=` `np.array(list1)`   `# count even numbers` `even_count ``=` `len``(np.where(arr ``%` `2` `=``=` `0``)[``0``])`   `# count odd numbers` `odd_count ``=` `len``(np.where(arr ``%` `2` `=``=` `1``)[``0``])`   `# print counts` `print``(``"Even numbers in the list: "``, even_count)` `print``(``"Odd numbers in the list: "``, odd_count)`

Output:

```Even numbers in the list:  3
Odd numbers in the list:  2```

Time Complexity: O(N), where N is the number of elements in the list.
Space Complexity: O(N), as we create a numpy array of size N.

### Method: Using Sum and len function

Approach:

• Initialize list.
• Initialize even_count and odd_count variables to store numbers.
• Use Sum method which counts 1 if the number in the list is odd and store the result in odd_count.
• Subtract the total length list to odd_count and store the value in even_count.
• Print event_count and odd_count.

## Python3

 `# Python program to count Even` `# and Odd numbers in a List`   `# list of numbers` `list1 ``=` `[``10``, ``21``, ``4``, ``45``, ``66``, ``93``, ``1``]`   `even_count, odd_count ``=` `0``, ``0`   `# Using sum function ` `odd_count ``=` `sum``(``1` `for` `i ``in` `list1 ``if` `i&``1``)` `even_count ``=` `len``(list1) ``-` `odd_count`   `print``(``"Even numbers in the list: "``, even_count)` `print``(``"Odd numbers in the list: "``, odd_count)`

Output:

```Even numbers in the list:  3
Odd numbers in the list:  4```

Time Complexity: O(n), where n is the length of the list.
Space Complexity: O(1), Because no extra space is used.

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