solve: sumOfTwoIntegers

Author: GaggleHelena

sum-of-two-integers/yolophg.py

@@ -0,0 +1,22 @@
+# Time Complexity: O(1) - fixed 32-bit operations, at most 32 iterations
+# Space Complexity: O(1) - only uses a few integer variables
+
+class Solution:
+    def getSum(self, a: int, b: int) -> int:
+        # 32-bit mask to keep numbers within range
+        mask = 0xFFFFFFFF
+        # max value for a signed 32-bit integer (2^31 - 1)
+        MAX = 0x7FFFFFFF   
+
+        # keep going until there's no carry left
+        while b != 0:  
+            # carry is AND operation, then shift left
+            carry = (a & b) << 1 
+            # XOR does the addition, keep it within 32 bits
+            a = (a ^ b) & mask    
+            # carry becomes the new b (loop continues if carry exists)
+            b = carry & mask      
+
+        # if a is greater than MAX, it's actually a negative number in 32-bit terms
+        # convert it to proper negative representation
+        return a if a <= MAX else ~(a ^ mask)