[summer daily question] Luogu p1601 a+b problem (high precision)

Topic link ：P1601 A+B Problem（ Hyperfine ） - Luogu | New ecology of computer science education (luogu.com.cn)

Title Description

High precision addition , amount to a+b problem, Don't worry about negative numbers .

Input format

Enter in two lines .a,b <= 10^500.

Output format

There is only one line of output , representative a+b  Value .

Examples #1

The sample input #1

1
1

Sample output #1

2

Examples #2

The sample input #2

1001
9099

Sample output #2

10100

AC code: 

#include<iostream>
#include<algorithm>
#include<string>

using namespace std;

string f(string a,string b)
{
	if(a=="0" && b=="0")
	{
		return "0";
	}
	int t1=a.size();
	int t2=b.size();
	int n=abs(t1-t2);
	
	for(int i=0;i<n;i++)
	{
		if(t1>=t2)
			b="0"+b;
		else
			a="0"+a;
	}
	string s; //  and  
	int c=0; //  carry 
	int d=0; //  Low position  
	int len=a.size()-1;
	for(int i=len;i>=0;i--)
	{
		d=(a[i]-'0'+b[i]-'0')%10+c;
		if(d==10)
		{
			c=1;
			s="0"+s;
			continue;
		}
		s=to_string(d)+s;
		c=(a[i]-'0'+b[i]-'0')/10;
		if(c==1 && i==0)
			s="1"+s;
	}
	if(s[0]=='0')
		s="1"+s;
	return s;
}

int main()
{
	string a,b;
	cin>>a>>b;
	cout<<f(a,b);
	
	return 0;
}