Sync LeetCode submission Runtime - 0 ms (100.00%), Memory - 17.7 MB (59.83%)

Author: jimit105

0066-plus-one/solution.py

@@ -1,21 +1,21 @@
-# Approach 1 - Schoolbook Addition with Carry
+# Approach 1: Schoolbook Addition with Carry
 
-# Time: O(N)
+# Time: O(n)
+# Space: O(1)
 
 class Solution:
     def plusOne(self, digits: List[int]) -> List[int]:
         n = len(digits)
-        
-        for i in range(n):
-            idx = n - 1 - i
-            
-            if digits[idx] == 9:
-                digits[idx] = 0
-                
-            else:
-                digits[idx] += 1
+
+        for i in range(n - 1, -1, -1):
+            if digits[i] < 9:
+                digits[i] += 1
                 return digits
-            
-        # if all digits are 9
+
+            # If current digit is 9, make it 0 and continue to next digit
+            digits[i] = 0
+
+        # If we're here, it means all digits were 9
+        # Need to add a new digit 1 at the beginning
         return [1] + digits