[2016-05-09][51nod][1005 大数加法]

• 时间:2016-05-09 18:20:09 星期一

• 题目编号:[2016-05-09][51nod][1005 大数加法]

• 题目大意:大数 A + B,支持负数

#include<cstdio>
#include<cstring>
#include<string>
#include<iostream>
#include<iomanip>
using namespace std;
const int DLEN = 4;
const int MAXN = 9999;
const int maxsize = 1E5;
class BigNum{
public:
        int a[5000];
        int len,flg;
        BigNum(){len = flg = 1;memset(a,0,sizeof(a));}
        BigNum(const BigNum & T):len(T.len),flg(T.flg){
                memset(a,0,sizeof(a));
                for(int i = 0 ; i < len;++i){
                        a[i] = T.a[i];
                }
        }
        friend int abscmp(const BigNum a,const BigNum b){//比较绝对值的大小
                int ln;
                if(a.len > b.len)        return 1;
                else if(a.len == b.len){
                        ln = a.len - 1;
                        while(a.a[ln] == b.a[ln] && ln >=0)        --ln;
                        if(ln >= 0 && a.a[ln] > b.a[ln])        return 1;
                        else return 0;
                }else return 0;                               
        }
        friend void sub(BigNum & t1, BigNum & t2){//t1 > t2,不考虑符号,t1 - t2,并且,并且结果直接在t1中生效
                int i,j,big;
                big = t1.len;
                for(i = 0 ; i < big; ++i){
                        if(t1.a[i] < t2.a[i]){
                                j = i + 1;
                                while(t1.a[j] == 0)        ++j;
                                t1.a[j--]--;
                                while(j > i)        t1.a[j--] += MAXN;
                                t1.a[i] += MAXN + 1 - t2.a[i];
                        }else t1.a[i] -= t2.a[i];
                }
                t1.len = big;
                while(t1.a[t1.len -1] == 0 && t1.len > 1){
                        --t1.len;
                        --big;
                }
        }                       
        BigNum operator + (const BigNum & T)const{        //相加
                if((flg == 0 && T.flg == 0) ||(flg && T.flg) ){
                        BigNum t(*this);
                        int big;
                        big = T.len > len ? T.len : len;
                        for(int i = 0 ; i < big; ++i){
                                t.a[i] += T.a[i];
                                if(t.a[i] > MAXN){
                                        ++t.a[i + 1];
                                        t.a[i] -= MAXN + 1;
                                }
                        }
                        if(t.a[big] != 0){
                                t.len = big + 1;
                        }else t.len = big;
                        t.flg = flg;
                        return t;                       
                }else {
                        int tflg;
                        BigNum a,b;
                        if(cmp(*this,T)){
                                a = *this;
                                b = T;
                        }else {
                                a = T;
                                b = *this;       
                        }
                        sub(a,b);
                        return a;                       
                }
        }
        friend        istream& operator >> (istream & in,BigNum &b){
                char ch[maxsize * 4];
                int i = -1;
                in >> ch;
                int l = strlen(ch);
                int count = 0,sum = 0;
                int ed = 0;
                if(ch[0] == '-'){
                        b.flg = 0;
                        ed = 1;
                }
                for(int i = l - 1 ; i >= ed ;){
                        sum = 0;
                        int t = 1;
                        for(int j = 0 ; j < 4 && i >= ed ; ++j,--i,t*=10){
                                sum += (ch[i] - '0') * t;
                        }
                        b.a[count++] =sum;
                }
                b.len = count++;
                return in;
        }
        friend ostream & operator << (ostream & out, const BigNum &b){
                int i;
                if(b.flg == 0)        out<<"-";       
                out<<b.a[b.len - 1];
                for(i = b.len - 2 ; i >=0 ; --i){
                        out<<setw(4)<<setfill('0')<<b.a[i];
                }
                return out;       
        }
};
int main(){
        BigNum a,b;
        cin>>a>>b;
        cout<<(a+b)<<"\n";
        return 0;
}

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