415. Add Strings

最新推荐文章于 2020-08-04 22:32:35 发布

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最新推荐文章于 2020-08-04 22:32:35 发布

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分类专栏： leetcode-easy

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博客要求对两个以字符串表示的非负整数求和。给出了相关限制条件，如两数长度小于5100，仅含数字且无前置零，同时禁止使用内置大整数库或直接将输入转换为整数。

Given two non-negative integers num1 and num2 represented as string, return the sum of num1 and num2.

Note:

The length of both num1 and num2 is < 5100.
Both num1 and num2 contains only digits 0-9.
Both num1 and num2 does not contain any leading zero.
You must not use any built-in BigInteger library or convert the inputs to integer directly.

class Solution {
public:
    string addStrings(string num1, string num2) {
        reverse(num1.begin(),num1.end());
        reverse(num2.begin(),num2.end());
        int sum=0,carry=0;
        string ans="";
        for(int i=0;i<num1.length()||i<num2.length();i++){
            sum=carry;
            if(i<num1.length()){
                sum=sum+num1[i]-'0';
            }
            if(i<num2.length()){
                sum=sum+num2[i]-'0';
            }
            ans=to_string(sum%10)+ans;
            carry=sum/10;
        }
        if(carry){
            ans=to_string(carry)+ans;
        }
        return ans;
    }
};