【Codevs 3115】高精度练习之减法

板子题~
// <H.cpp> - Sun Oct  9 12:58:23 2016

// This file is made by YJinpeng，created by XuYike's black technology automatically.

// Copyright (C) 2016 ChangJun High School, Inc.

// I don't know what this program is.

#include <iostream>

#include <vector>

#include <algorithm>

#include <cstring>

#include <cstdio>

#include <cstdlib>

#include <cmath>

#define MOD 1000000007

#define INF 1e9

#define IN inline

#define RG register

using namespace std;

typedef long long LL;

typedef long double LB;

const int MAXN=;

const int MAXM=;

inline int max(int &x,int &y) {return x>y?x:y;}

inline int min(int &x,int &y) {return x<y?x:y;}

inline LL gi() {

    register LL w=,q=;register char ch=getchar();

    while((ch<''||ch>'')&&ch!='-')ch=getchar();

    if(ch=='-')q=,ch=getchar();

    while(ch>=''&&ch<='')w=w*+ch-'',ch=getchar();

    return q?-w:w;

}

const int _bod_=;

struct BN{

    static const int N=;int a[N];char s[N];

    int& operator [](int n){return a[n];}

    bool operator <(BN b) const{

        if(a[]<b[])return ;

        if(a[]>b[])return ;

        for(int i=a[];i>=;i--){

            if(a[i]>b[i])return ;

            if(a[i]<b[i])return ;

        }

        return ;

    }

    BN operator -(BN b) const{

        BN ans=*this;int q=;

        if(ans<b)swap(ans,b),q=-;

        for(int i=;i<=ans[];i++){

            ans[i]=ans[i]-b[i];

            if(ans[i]<){ans[i+]--;ans[i]+=_bod_;}

        }

        while(ans[]&&!ans[ans[]])ans[]--;

        for(int i=;i<=ans[];i++)ans[i]*=q;

        return ans;

    }

    void read(){

        scanf("%s",s);a[]=strlen(s);

        for(int i=;i<=a[];i++)a[i]=s[a[]-i]-'';

    }

    void pri(){printf("%d",a[a[]]);for(int i=a[]-;i>=;i--)printf("%.1d",a[i]);}

}a,b;

int main()

{

    freopen("3115.in","r",stdin);

    freopen("3115.out","w",stdout);

    a.read(),b.read();

    if(a<b)printf("-"),(b-a).pri();else (a-b).pri();

    return ;

}