43. Multiply Strings

弃疗题 就是大数乘法。。。。网上的代码

class Solution {public:    string multiply(string num1, string num2) {        string result="";        int m=num1.size(),n=num2.size();        vector<int> ans(m+n,0);        reverse(num1.begin(),num1.end());        reverse(num2.begin(),num2.end());        for(int i=0;i<m;i++){            for(int j=0;j<n;j++){                ans[i+j]+=(num1[i]-'0')*(num2[j]-'0');                ans[i+j+1]+=ans[i+j]/10;                ans[i+j]%=10;            }        }        int i=m+n-1;        while(i>0 && ans[i]==0) i--;        for(;i>=0;i--) result+=to_string(ans[i]);        return result;    }};