415.md

415 Add Strings

Description

link

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Solution

• See Code

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Code

O(n)

class Solution:
    def addStrings(self, num1: str, num2: str) -> str:
        if len(num1) < len(num2):
            num1, num2 = num2, num1
            
        num1, num2 = num1[::-1], num2[::-1]
        add = 0
        res = []
        for i in range(len(num1)):
            if i < len(num2):
                s = int(num1[i]) + int(num2[i]) + add
            else:
                s = int(num1[i]) + add
            add, num = s //10, s % 10
            res.append(str(num))
        
        if add:
            res.append(str(add))
            
        return ''.join(res[::-1])