二进制表示

yingl · yingl · commit 00c1b8e3fd82 · 2016-08-12T11:18:25.000+08:00
diff --git a/binary_representation.py b/binary_representation.py
@@ -0,0 +1,57 @@
+# -*- coding: utf-8 -*-
+
+class Solution:
+    #@param n: Given a decimal number that is passed in as a string
+    #@return: A string
+    def binaryRepresentation(self, n):
+        # write you code here
+        # TODO: 添加注释
+        bin_val = []
+        int_digits = 0
+        for i in xrange(len(n)):
+            if n[i] != '.':
+                int_digits += 1
+            else:
+                break
+        int_part = self.int(n, 0, int_digits)
+        float_part = self.int(n, int_digits + 1, len(n))
+        if int_part == 0:
+            bin_val.append('0')
+        else:
+            while int_part != 0:
+                bin_val.append('1' if (int_part % 2) == 1 else '0')
+                int_part /= 2
+            bin_val.reverse()
+        if float_part > 0:
+            bin_val.append('.')
+            bin_float_digits = 0
+            adjust = 0
+            while ((int_digits + 1+ adjust) < len(n)) and (n[int_digits + 1 + adjust] == '0'):
+                adjust += 1
+            round_up = self.roundUp(float_part, adjust)
+            while float_part > 0:
+                float_part_2 = float_part * 2
+                bin_val.append('1' if float_part_2 >= round_up else '0')
+                bin_float_digits += 1
+                if bin_float_digits > 32:
+                    return 'ERROR'
+                float_part = (float_part_2 - round_up) if float_part_2 >= round_up else float_part_2
+        return ''.join(bin_val)
+
+    def int(self, number, start, end):  # 字符串转整数
+        ret = 0
+        while start < end:
+            ret = ret * 10 + int(number[start])
+            start += 1
+        return ret
+
+    def roundUp(self, val, adjust): # 向上取整
+        ret = 1
+        while val > 0:
+            ret *= 10
+            val /= 10
+        i = 0
+        while i < adjust:
+            ret *= 10
+            i += 1
+        return ret
