【洛谷p2142】高精度减法

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<string>
#include<cmath>
using namespace std;
int a[100000001],b[10000001],c[10000001],lena,lenb,lenc,i;
char n[100001],n1[100001],n2[100001];
int main()
{
    scanf("%s",n1);
    scanf("%s",n2);
    if(strlen(n1)<strlen(n2)||(strlen(n1)==strlen(n2)&&strcmp(n1,n2)<0))
    {
        strcpy(n,n1);
        strcpy(n1,n2);
        strcpy(n2,n);
        cout<<"-";
    }
    lena=strlen(n1);lenb=strlen(n2);
    for(i=0;i<=lena-1;i++)a[lena-i]=int(n1[i]-'0');
    for(i=0;i<=lenb-1;i++)b[lenb-i]=int(n2[i]-'0');
    i=1;
    while(i<=lena||i<=lenb)
    {
        if(a[i]<b[i])
        {
            a[i]+=10;
            a[i+1]--;
        }
        c[i]=a[i]-b[i];
        i++;
    }
    lenc=i;
    while((c[lenc]==0)&&(lenc>1))lenc--;
    for(i=lenc;i>=1;i--)cout<<c[i];
    cout<<endl;
    return 0;
}
//代码已ac