Given two non-negative integers, num1
and num2
represented as string, return the sum of num1
and num2
as a string.
You must solve the problem without using any built-in library for handling large integers (such as BigInteger
). You must also not convert the inputs to integers directly.
其实就是高精度加法,这里按照竖式加法即可,其中 \(top\) 表示进位
class Solution { private: string ans=""; public: string addStrings(string num1, string num2) { int n1 = num1.size(); int n2 = num2.size(); int top = 0; int pos1=n1-1, pos2=n2-1; while(1){ int s1=0, s2=0; if(pos1>=0)s1=num1[pos1]-'0'; if(pos2>=0)s2=num2[pos2]-'0'; int sum = s1+s2+top; if(sum<10){ ans= char('0'+sum)+ans; top=0; } else{ ans= char(sum%10+'0')+ans;top=1; } pos1--;pos2--; if(pos1<0 && pos2<0) break; } if(top){ ans=char('0'+top)+ans; } //reverse(ans.begin(), ans.end()); return ans; } };