LeetCode-Multiply Strings实现大数的乘法

Given two numbers represented as strings, return multiplication of the numbers as a string.

Note: The numbers can be arbitrarily large and are non-negative.

题目当中主要是需要两个大数的乘法，一般大数都是用字符串进行保存

代码比较简单，主要是利用了一个vector反向的存储了计算的结果，然后reverse到string当中进行输出

这里当然可以直接定义一个string然后其中进行操作，那么就会出现很多char和int之间的转换，感觉比较麻烦

class Solution {
public:
    string multiply(string num1, string num2) {
        if(num1=="0" || num2=="0") return "0";  
        int length1 = num1.size();
        int length2 = num2.size();
        vector<int> mulResult(length1+length2,0);//<used to restore the multi result
        int i = 0,j = 0;
        int temp = 0;
        int nextNum = 0; //<10位数
        int index = 0;
        int n1;
        int n2;
        for(i = length2-1; i >= 0; i--)
        {
            index = (length2-1)-i;
            n2 = num2[i]-'0';
            nextNum = 0;
            for(j = length1-1; j >= 0;j--)
            {
                n1 = num1[j]-'0';
                temp = n2*n1;
                temp += nextNum; //<加上上一次进位的数
                temp += mulResult[index];  //<加上之前计算的结果
                mulResult[index] = (temp%10);
                nextNum = temp/10;
                index++;
            }
            if(nextNum>0)
            {
                mulResult[index] = nextNum;
                index++;
            }
            
        }
        string result = "";
        for(i = index-1; i>=0;i--)
        {
            result += ('0'+ mulResult[i]);
        }
        return result;
    }
};