hexadecimal

Author: idf

405 Convert a Number to Hexadecimal.py

@@ -0,0 +1,65 @@
+"""
+Given an integer, write an algorithm to convert it to hexadecimal. For negative integer, two's complement method is
+used.
+
+Note:
+
+All letters in hexadecimal (a-f) must be in lowercase.
+The hexadecimal string must not contain extra leading 0s. If the number is zero, it is represented by a single zero
+character '0'; otherwise, the first character in the hexadecimal string will not be the zero character.
+The given number is guaranteed to fit within the range of a 32-bit signed integer.
+You must not use any method provided by the library which converts/formats the number to hex directly.
+Example 1:
+
+Input:
+26
+
+Output:
+"1a"
+Example 2:
+
+Input:
+-1
+
+Output:
+"ffffffff"
+"""
+__author__ = 'Daniel'
+
+
+class Solution(object):
+    def toHex(self, num):
+        """
+        All use bit manipulation
+        :type num: int
+        :rtype: str
+        """
+        ret = []
+        while len(ret) < 8 and num:
+            ret.append(self.encode(num & 0xf))
+            num >>= 4
+
+        return ''.join(ret[::-1]) or '0'
+
+    def toHexNormal(self, num):
+        """
+        Python arithmetic handles the negative number very well
+        :type num: int
+        :rtype: str
+        """
+        ret = []
+        while len(ret) < 8 and num:
+            ret.append(self.encode(num % 16))
+            num /= 16
+
+        return ''.join(ret[::-1]) or '0'
+
+    def encode(self, d):
+        if 0 <= d < 10:
+            return str(d)
+
+        return chr(ord('a') + d - 10)
+
+
+if __name__ == "__main__":
+    assert Solution().toHex(-1) == 'ffffffff'