fix is_ip_v4_address_valid.py

maths/is_ip_v4_address_valid.py

@@ -1,13 +1,17 @@
 """
+wiki: https://en.wikipedia.org/wiki/IPv4
+
 Is IP v4 address valid?
-A valid IP address must be four octets in the form of A.B.C.D,
-where A,B,C and D are numbers from 0-254
-for example: 192.168.23.1, 172.254.254.254 are valid IP address
-             192.168.255.0, 255.192.3.121 are invalid IP address
+A valid IP address must be four numbers in the form of A.B.C.D,
+where A,B,C and D are numbers from 0-255
+
+for example:
+    192.168.23.1, 172.254.254.254 are valid IP address
+    192.168.01.0, 256.192.3.121 are invalid IP address
 """
 
 
-def is_ip_v4_address_valid(ip_v4_address: str) -> bool:
+def is_ip_v4_address_valid(ip: str) -> bool:
     """
     print "Valid IP address" If IP is valid.
     or
@@ -17,12 +21,15 @@ def is_ip_v4_address_valid(ip_v4_address: str) -> bool:
     True
 
     >>> is_ip_v4_address_valid("192.255.15.8")
-    False
+    True
 
     >>> is_ip_v4_address_valid("172.100.0.8")
     True
 
-    >>> is_ip_v4_address_valid("254.255.0.255")
+    >>> is_ip_v4_address_valid("0.0.0.0")
+    True
+
+    >>> is_ip_v4_address_valid("254.256.0.255")
     False
 
     >>> is_ip_v4_address_valid("1.2.33333333.4")
@@ -40,17 +47,33 @@ def is_ip_v4_address_valid(ip_v4_address: str) -> bool:
     >>> is_ip_v4_address_valid("1.2.A.4")
     False
 
-    >>> is_ip_v4_address_valid("0.0.0.0")
-    True
-
-    >>> is_ip_v4_address_valid("1.2.3.")
+    >>> is_ip_v4_address_valid("1.2.3.05")
     False
     """
-    octets = [int(i) for i in ip_v4_address.split(".") if i.isdigit()]
-    return len(octets) == 4 and all(0 <= int(octet) <= 254 for octet in octets)
+
+    parts = ip.split(".")
+
+    if len(parts) != 4:
+        return False
+
+    for part in parts:
+        if not part:
+            return False
+
+        for i in range(len(part)):
+            if not part[i].isdigit():
+                return False
+
+        if part[0] == "0" and len(part) > 1:
+            return False
+
+        if not (0 <= int(part) <= 255):
+            return False
+
+    return True
 
 
 if __name__ == "__main__":
     ip = input().strip()
-    valid_or_invalid = "valid" if is_ip_v4_address_valid(ip) else "invalid"
-    print(f"{ip} is a {valid_or_invalid} IP v4 address.")
+    result = "valid" if is_ip_v4_address_valid(ip) else "invalid"
+    print(f"{ip} is a {result} IPv4 address.")