高精度模板

用类实现的高精度模板实在是太臃肿了，用过程实现一次方便记忆

#include<iostream>
#include<algorithm>
#include<cstring>
#include<iomanip>
using namespace std;

const int MAXN=1000;
const int DLEN=4;
const int WIDE=10000;
class BigNum
{
public:
    int NUM[MAXN];
    int L;
    bool flag;
    BigNum(){memset(NUM,0,sizeof(NUM));L=1;flag=0;}
    BigNum(const BigNum &T){memcpy(NUM,T.NUM,sizeof(NUM));L=T.L;flag=T.flag;}
    BigNum(int n){memset(NUM,0,sizeof(NUM));NUM[0]=n;L=1;while(NUM[L-1]>=WIDE){NUM[L]+=NUM[L-1]/WIDE;NUM[L-1]%=WIDE;L++;}flag=0;}
};

void Input(string s,BigNum &T)
{
    int k=1,num=0;
    memset(T.NUM,0,sizeof(int)*MAXN);T.L=0;
    for(int i=s.size()-1;i>=0;i--)
    {
        if(k==WIDE) T.NUM[T.L++]=num,num=0,k=1;
        num+=k*(s[i]-'0');
        k*=10;
    }
    if(num>0) T.NUM[T.L++]=num;
}

void Output(const BigNum T)
{
    if(T.flag==1) cout<<'-';
    cout<<T.NUM[T.L-1];
    for(int i=T.L-2;i>=0;i--)
    {
        cout.width(DLEN);
        cout.fill('0');
        cout<<T.NUM[i];
    }
}

bool cmp(const BigNum A,const BigNum B)
{
    if(A.L!=B.L) return A.L<B.L;
    for(int i=A.L-1;i>=0;i--)
        if(A.NUM[i]!=B.NUM[i])
            return A.NUM[i]<B.NUM[i];
    return 0;
}

BigNum Add(const BigNum A,const BigNum B)
{
    BigNum C;
    int L=max(A.L,B.L);C.L=L;
    for(int i=0;i<L;i++)
    {
        C.NUM[i]+=A.NUM[i]+B.NUM[i];
        if(C.NUM[i]>=WIDE)
            C.NUM[i]-=WIDE,C.NUM[i+1]++;
    }
    if(C.NUM[L]>0) C.L++;
    return C;
}

BigNum Add(const BigNum A,int B)
{
    BigNum C(A);
    C.NUM[0]+=B;
    for(int i=0;i<C.L;i++)
        if(C.NUM[i]>=WIDE)
            C.NUM[i+1]+=C.NUM[i]/WIDE,C.NUM[i]%=WIDE;
    if(C.NUM[C.L]>0) C.L++;
    return C;
}

BigNum Dec(BigNum A,BigNum B)
{
    BigNum *X=&A,*Y=&B,C;
    int L=max(X->L,Y->L);
    C.L=L;
    if(cmp(*X,*Y)) swap(X,Y),C.flag=1;
    for(int i=0;i<L;i++)
    {
        C.NUM[i]+=X->NUM[i]-Y->NUM[i];
        if(C.NUM[i]<0)
            C.NUM[i]+=WIDE,C.NUM[i+1]--;
    }
    while(C.NUM[C.L-1]==0) C.L--;
    return C;
}

BigNum Dec(BigNum A,int B)
{
    BigNum C(A);
    C.NUM[0]-=B;
    for(int i=0;i<C.L;i++)
        if(C.NUM[i]<0)
            C.NUM[i+1]+=C.NUM[i]/WIDE-1,C.NUM[i]=WIDE-abs(C.NUM[i]%WIDE);
    if(C.NUM[C.L-1]==0) C.L--;
    return C;
}

BigNum Mult(const BigNum A,const BigNum B)
{
    BigNum C;
    for(int i=0;i<A.L;i++)
        for(int j=0;j<B.L;j++)
        {
            C.L=i+j;
            C.NUM[C.L]+=A.NUM[i]*B.NUM[j];
            if(C.NUM[C.L]>=WIDE)
                C.NUM[C.L+1]+=C.NUM[C.L]/WIDE,C.NUM[C.L]%=WIDE;
        }
    C.L=A.L+B.L;
    if(C.NUM[C.L-1]==0) C.L--;
    return C;
}

BigNum Mult(const BigNum A,int B)
{
    BigNum C(A);
    int i,tmp,k=0;
    for(i=0;i<C.L||k;i++)
    {
        tmp=C.NUM[i]*B+k;
        k=tmp/WIDE;
        C.NUM[i]=tmp%WIDE;
    }
    C.L=i;
    return C;
}

BigNum Div2(const BigNum A)
{
    BigNum C(A);
    for(int i=C.L-1;i>=0;i--)
    {
        if(C.NUM[i]%2&&i>0)
            C.NUM[i-1]+=WIDE;
        C.NUM[i]/=2;
    }
    if(C.NUM[C.L-1]==0) C.L--;
    return C;
}

BigNum Div(const BigNum A,const BigNum B)
{
    BigNum L(1),R(A),T;
    while(cmp(Add(L,1),R))
    {
        T=Div2(Add(L,R));
        if(cmp(A,Mult(T,B)))
            R=T;
        else 
            L=T;
    }
    return L;
}

BigNum Div(const BigNum A,int B)
{
    BigNum C(A);
    int k=0;
    for(int i=C.L-1;i>=0;i--)
    {
        k=k*WIDE+C.NUM[i];
        C.NUM[i]=k/B;
        k%=B;
    }
    while(C.NUM[C.L-1]==0) C.L--;
    return C;
}

BigNum A,B,C;

int main()
{
    string s1,s2;
    cin>>s1>>s2;
    Input(s1,A);
    Input(s2,B);
    C=Add(A,B);
    Output(C);
    return 0;
}