Leetcode-415. Add Strings_carry number csdn-优快云博客

本文链接：https://blog.youkuaiyun.com/mcf171/article/details/52770031

本文介绍了一道LeetCode在线笔试题目，即两个非负数字符串形式的数字相加。文章提供了完整的Java代码实现，并解释了如何通过逐位相加并考虑进位的方式解决该问题。代码中不含内置的大整数库使用，也不直接将输入转换为整数。

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前言：正好碰见Leetcode有一次在线笔试，测试一下，还是挺开心的，全做出来了Rank：98/869。如有错误欢迎指正。博主首发优快云，mcf171专栏。

博客链接：mcf171的博客

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Given two non-negative numbers 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.

这个题目挺简单的，没啥好说的。

public class Solution {
    public String addStrings(String num1, String num2) {

        StringBuffer sb = new StringBuffer("");
        int carryNumber = 0, i = num1.length() - 1, j = num2.length() - 1;

        while( i >= 0 && j >= 0){

            int results = (num1.charAt(i) - '0') + (num2.charAt(j) - '0') + carryNumber;
            sb.insert(0,results%10);
            carryNumber = results/10;
            i--;j--;
        }

        while( i >= 0){

            int results = (num1.charAt(i) - '0') + carryNumber;
            sb.insert(0,results%10);
            carryNumber = results/10;
            i--;
        }

        while( j >= 0){
            int results = (num2.charAt(j) - '0') + carryNumber;
            sb.insert(0,results%10);
            carryNumber = results/10;
            j--;
        }

        if( carryNumber == 1) sb.insert(0,carryNumber);

        return sb.toString();


    }
}