sock_merchant.py: Matching socks by color

DIRECTORY.md

@@ -39,6 +39,7 @@
   * [Binary Xor Operator](https://github.com/TheAlgorithms/Python/blob/master/bit_manipulation/binary_xor_operator.py)
   * [Count 1S Brian Kernighan Method](https://github.com/TheAlgorithms/Python/blob/master/bit_manipulation/count_1s_brian_kernighan_method.py)
   * [Count Number Of One Bits](https://github.com/TheAlgorithms/Python/blob/master/bit_manipulation/count_number_of_one_bits.py)
+  * [Gray Code Sequence](https://github.com/TheAlgorithms/Python/blob/master/bit_manipulation/gray_code_sequence.py)
   * [Reverse Bits](https://github.com/TheAlgorithms/Python/blob/master/bit_manipulation/reverse_bits.py)
   * [Single Bit Manipulation Operations](https://github.com/TheAlgorithms/Python/blob/master/bit_manipulation/single_bit_manipulation_operations.py)
 
@@ -63,7 +64,7 @@
   * [Baconian Cipher](https://github.com/TheAlgorithms/Python/blob/master/ciphers/baconian_cipher.py)
   * [Base16](https://github.com/TheAlgorithms/Python/blob/master/ciphers/base16.py)
   * [Base32](https://github.com/TheAlgorithms/Python/blob/master/ciphers/base32.py)
-  * [Base64 Encoding](https://github.com/TheAlgorithms/Python/blob/master/ciphers/base64_encoding.py)
+  * [Base64](https://github.com/TheAlgorithms/Python/blob/master/ciphers/base64.py)
   * [Base85](https://github.com/TheAlgorithms/Python/blob/master/ciphers/base85.py)
   * [Beaufort Cipher](https://github.com/TheAlgorithms/Python/blob/master/ciphers/beaufort_cipher.py)
   * [Bifid](https://github.com/TheAlgorithms/Python/blob/master/ciphers/bifid.py)
@@ -219,6 +220,7 @@
   * Filters
     * [Bilateral Filter](https://github.com/TheAlgorithms/Python/blob/master/digital_image_processing/filters/bilateral_filter.py)
     * [Convolve](https://github.com/TheAlgorithms/Python/blob/master/digital_image_processing/filters/convolve.py)
+    * [Gabor Filter](https://github.com/TheAlgorithms/Python/blob/master/digital_image_processing/filters/gabor_filter.py)
     * [Gaussian Filter](https://github.com/TheAlgorithms/Python/blob/master/digital_image_processing/filters/gaussian_filter.py)
     * [Median Filter](https://github.com/TheAlgorithms/Python/blob/master/digital_image_processing/filters/median_filter.py)
     * [Sobel Filter](https://github.com/TheAlgorithms/Python/blob/master/digital_image_processing/filters/sobel_filter.py)
@@ -492,6 +494,7 @@
   * [Integration By Simpson Approx](https://github.com/TheAlgorithms/Python/blob/master/maths/integration_by_simpson_approx.py)
   * [Is Ip V4 Address Valid](https://github.com/TheAlgorithms/Python/blob/master/maths/is_ip_v4_address_valid.py)
   * [Is Square Free](https://github.com/TheAlgorithms/Python/blob/master/maths/is_square_free.py)
+  * [Iterative Pair](https://github.com/TheAlgorithms/Python/blob/master/maths/iterative_pair.py)
   * [Jaccard Similarity](https://github.com/TheAlgorithms/Python/blob/master/maths/jaccard_similarity.py)
   * [Kadanes](https://github.com/TheAlgorithms/Python/blob/master/maths/kadanes.py)
   * [Karatsuba](https://github.com/TheAlgorithms/Python/blob/master/maths/karatsuba.py)
@@ -511,6 +514,7 @@
   * [Modular Exponential](https://github.com/TheAlgorithms/Python/blob/master/maths/modular_exponential.py)
   * [Monte Carlo](https://github.com/TheAlgorithms/Python/blob/master/maths/monte_carlo.py)
   * [Monte Carlo Dice](https://github.com/TheAlgorithms/Python/blob/master/maths/monte_carlo_dice.py)
+  * [Nevilles Method](https://github.com/TheAlgorithms/Python/blob/master/maths/nevilles_method.py)
   * [Newton Raphson](https://github.com/TheAlgorithms/Python/blob/master/maths/newton_raphson.py)
   * [Number Of Digits](https://github.com/TheAlgorithms/Python/blob/master/maths/number_of_digits.py)
   * [Numerical Integration](https://github.com/TheAlgorithms/Python/blob/master/maths/numerical_integration.py)

maths/iterative_pair.py

@@ -0,0 +1,30 @@
+"""Count equal element pairs in the given array"""
+
+import doctest
+from collections import Counter
+
+
+def sock_merchant(ar: list[int]) -> int:
+    """
+    >>> sock_merchant([10, 20, 20, 10, 10, 30, 50, 10, 20])
+    3
+    >>> sock_merchant([1, 1, 3, 3])
+    2
+
+    """
+
+    i = 0
+    occur = Counter(ar)
+
+    for x in occur.values():
+        i += x // 2
+    return i
+
+
+if __name__ == "__main__":
+
+    array = list(map(int, input().rstrip().split()))
+
+    result = sock_merchant(array)
+    print(result)
+    doctest.testmod()