Merge pull request #19 from miguelHx/miguel_1.3_URLify

Miguel 1.3 - URLify [Python]

Author: fvntr

Python/chapter01/1.3 - URLify/miguel_1.3_sol.py

@@ -0,0 +1,108 @@
+"""
+Python version 3.7.0
+1.3 - URLify
+Write a method to replace all spaces in a string with "%20".
+The following only applies to C/C++: "You may assume that the string has sufficient
+space at the end to hold the additional characters, and that you are given the "true" length of the string"
+(Note: If implementing in Java, please use a character array so that you can perform this operation in place)
+Since we are using python, no need to use true length.  I will have two functions, one with
+true_length and the other without.
+"""
+import unittest
+from typing import List
+
+
+def urlify(s: str) -> str:
+    """
+    Given a string, this function will return a new string
+    that replaces all of the spaces of the input string with '%20'.
+    :param s: the original string to 'urlify'
+    :return: string with each space from s replaced with '%20'
+    """
+    buf = ['\x00'] * (len(s) * 3)
+    for i, c in enumerate(s):
+        buf[i] = c
+
+    def _challenge(buf: List[str], original_length: int) -> None:
+        """
+        Your code here. Challenge rules:
+        * You can only reference |buf| and |original_length|, not |s|.
+        * You can only allocate O(1) additional memory
+        * You need to modify |buf| in-place so that the right answer is returned.
+        * You cannot modify any part of the wrapper function.
+        :param buf: buffer containing characters
+        :param original_length: original length of string
+        :return: None
+        """
+        space_count = 0
+        for j in range(original_length):
+            if buf[j] == ' ':
+                space_count += 1
+
+        chars_per_space = 2
+        idx = original_length + space_count * chars_per_space
+        for i in range(original_length-1, -1, -1):
+            if buf[i] == ' ':
+                buf[idx-1] = '0'
+                buf[idx-2] = '2'
+                buf[idx-3] = '%'
+                idx -= 3
+                continue
+            buf[idx-1] = buf[i]
+            idx -= 1
+    _challenge(buf, len(s))
+    return ''.join(buf).rstrip('\x00')
+
+
+def urlify_no_true_length(s: str) -> str:
+    """
+    This is the version of urlify without the true_length argument.
+    Given a string and it's "true" length, this function will return a new string
+    that replaces all of the spaces of the input string with '%20'.
+    Note that this will return a different result than the other urlify
+    if the other urlify's true length truncates the string with chars left over.
+    Precondition(s):
+    - length of s <= true_length
+    :param s: the original string to 'urlify'
+    :return: string with each space from s replaced with '%20'
+    """
+    output = []
+    for c in s:
+        if c == ' ':
+            output.append("%20")
+            continue
+        output.append(c)
+    return ''.join(output)
+
+
+class TestUrlifyFunction(unittest.TestCase):
+    def test_urlify(self):
+        cases = [
+            ("Mr John Smith", "Mr%20John%20Smith"),
+            ("Miguel Hernandez", "Miguel%20Hernandez"),
+            (" Techqueria", "%20Techqueria"),
+            ("a b c d e f g h", "a%20b%20c%20d%20e%20f%20g%20h"),
+            ("ihavenospaces", "ihavenospaces"),
+            ("nospaces", "nospaces"),
+            (" ", "%20")
+        ]
+        for s, expected in cases:
+            self.assertEqual(urlify(s), expected, msg=s)
+
+    def test_urlify_no_true_length(self):
+        cases = [
+            ("Mr John Smith", "Mr%20John%20Smith"),
+            ("Miguel Hernandez", "Miguel%20Hernandez"),
+            (" Techqueria ", "%20Techqueria%20"),
+            ("a b c d e f g h", "a%20b%20c%20d%20e%20f%20g%20h"),
+            ("a b c d e f g h ignore this", "a%20b%20c%20d%20e%20f%20g%20h%20ignore%20this"),
+            ("ihavenospaces", "ihavenospaces"),
+            ("nospacesIgnoreme", "nospacesIgnoreme"),
+            (" ", "%20")
+        ]
+        for s, expected in cases:
+            self.assertEqual(urlify_no_true_length(s), expected, msg=s)
+
+
+if __name__ == '__main__':
+    unittest.main()