bitwise

interview_cake/bitwise_stuff/count_bits.py

@@ -0,0 +1,37 @@
+#!/usr/bin/python
+
+''' This method returns the number of bits that are necessary to change to convert two
+    numbers A and B:
+    1) XOR
+    2) count 1s
+'''
+
+def count_bits_swap2(a, b):
+    count = 0
+    m = a^b
+    while m:
+        count +=1
+        m = m & (m-1)
+    return count
+
+
+
+def count_bits_swap(a, b):
+    m = a^b
+    return count_1s(m)
+
+
+def count_1s(m):
+    count = 0
+    while m:
+        if m& 1 :
+            count +=1
+        m >>= 1
+    return count
+
+
+if __name__ == '__main__':
+    a = int('10010000', 2)
+    b = int('01011010', 2)
+    print count_bits_swap(a, b)  #4
+    print count_bits_swap2(a, b)  #4