Update is_palindrome.py (TheAlgorithms#8022)

Author: abhishekmulik

strings/is_palindrome.py

@@ -16,7 +16,24 @@ def is_palindrome(s: str) -> bool:
     # Since punctuation, capitalization, and spaces are often ignored while checking
     # palindromes, we first remove them from our string.
     s = "".join(character for character in s.lower() if character.isalnum())
-    return s == s[::-1]
+    # return s == s[::-1] the slicing method
+    # uses extra spaces we can
+    # better with iteration method.
+
+    end = len(s) // 2
+    n = len(s)
+
+    # We need to traverse till half of the length of string
+    # as we can get access of the i'th last element from
+    # i'th index.
+    # eg: [0,1,2,3,4,5] => 4th index can be accessed
+    # with the help of 1st index (i==n-i-1)
+    # where n is length of string
+
+    for i in range(end):
+        if s[i] != s[n - i - 1]:
+            return False
+    return True
 
 
 if __name__ == "__main__":