【CODEVS3115】高精度练习之减法

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
char Sa[510],Sb[510];
int a[510],b[510];
int main()
{
    cin>>Sa>>Sb;
    int aLen=strlen(Sa),bLen=strlen(Sb);
    int l=max(aLen,bLen);
    if (bLen>aLen || (aLen==bLen && !strcmp(Sa,Sb)))
    {
        swap(Sa,Sb);
        swap(aLen,bLen);
        cout<<"-";
    }
    for (int i=1;i<=aLen;i++) a[i]=Sa[aLen-i]-‘0‘;
    for (int i=1;i<=bLen;i++) b[i]=Sb[bLen-i]-‘0‘;
    for (int i=1;i<=l;i++)
    {
        a[i]=a[i]-b[i];
        if (a[i]<0)
        {
            a[i]+=10;
            a[i+1]--; 
        }                                                              
    }
    while (!a[l]) l--;
    for (int i=l;i>=1;i--) cout<<a[i];
    return 0;
}