Add One To Number

Author: anantkaushik

Python/Interviewbit/Arrays/add-one-to-number.py

@@ -0,0 +1,46 @@
+"""
+Problem Link: https://www.interviewbit.com/problems/add-one-to-number/
+
+Given a non-negative number represented as an array of digits,
+add 1 to the number ( increment the number represented by the digits ).
+The digits are stored such that the most significant digit is at the head of the list.
+
+Example:
+If the vector has [1, 2, 3]
+the returned vector should be [1, 2, 4]
+as 123 + 1 = 124.
+
+NOTE: Certain things are intentionally left unclear in this question which you should practice 
+asking the interviewer.
+For example, for this problem, following are some good questions to ask :
+Q : Can the input have 0’s before the most significant digit. Or in other words, is 0 1 2 3 a 
+valid input?
+A : For the purpose of this question, YES
+Q : Can the output have 0’s before the most significant digit? Or in other words, is 0 1 2 4 
+a valid output?
+A : For the purpose of this question, NO. Even if the input has zeroes before the most significant 
+digit.
+"""
+class Solution:
+    # @param A : list of integers
+    # @return a list of integers
+    def plusOne(self, A):
+        rem = 0
+        carry = 1
+        i = len(A) - 1
+        while i >= 0:
+            if A[i] < 9:
+                A[i] += 1
+                carry = 0
+                break
+            else:
+                A[i] = 0
+            i -= 1
+        
+        if carry:
+            A.insert(0, 1)
+        i = 0
+        while i < len(A) and A[i] == 0:
+            i += 1
+            
+        return A[i:]