bign 类代码

痛定思痛。 2022-02-14 00:01 172阅读 0赞

算法入门经典中bign类代码：

#include<cstdio>
    #include<iostream>
    #include<cstring>
    using namespace std;
    const int maxn = 200;
    struct bign
    {
        int len, s[maxn];
    bign()
    {
        memset(s, 0, sizeof(s));
        len = 1;
    }
    bign(int num) {
        *this = num;
    }
    bign(const char* num) {
        *this = num;
    }
    bign operator = (int num) {
        char s[maxn];
        sprintf(s, "%d", num);
        *this = s;
        return *this;
    }
    bign operator = (const char* num) {
        len = strlen(num);
        for(int i = 0; i < len; i++) s[i] = num[len-i-1] - '0';
        return *this;
    }
    string str() const {
        string res = "";
        for(int i = 0; i < len; i++) res = (char)(s[i] + '0') + res;
        if(res == "") res = "0";
        return res;
    }
    bign operator + (const bign& b) const{
        bign c;
        c.len = 0;
        for(int i = 0, g = 0; g || i < max(len, b.len); i++) {
          int x = g;
          if(i < len) x += s[i];
          if(i < b.len) x += b.s[i];
          c.s[c.len++] = x % 10;
          g = x / 10;
        }
        return c;
    }
    void clean() {
        while(len > 1 && !s[len-1]) len--;
    }
    bign operator * (const bign& b) {
        bign c; c.len = len + b.len;
        for(int i = 0; i < len; i++)
          for(int j = 0; j < b.len; j++)
            c.s[i+j] += s[i] * b.s[j];
        for(int i = 0; i < c.len-1; i++){
          c.s[i+1] += c.s[i] / 10;
          c.s[i] %= 10;
        }
        c.clean();
        return c;
    }
    bign operator - (const bign& b) {
        bign c; c.len = 0;
        for(int i = 0, g = 0; i < len; i++) {
          int x = s[i] - g;
          if(i < b.len) x -= b.s[i];
          if(x >= 0) g = 0;
          else {
            g = 1;
            x += 10;
          }
          c.s[c.len++] = x;
        }
        c.clean();
        return c;
    }
    bool operator < (const bign& b) const{
        if(len != b.len) return len < b.len;
        for(int i = len-1; i >= 0; i--)
          if(s[i] != b.s[i]) return s[i] < b.s[i];
        return false;
    }
    bool operator > (const bign& b) const{
        return b < *this;
    }
    bool operator <= (const bign& b) {
        return !(b > *this);
    }
    bool operator == (const bign& b) {
        return !(b < *this) && !(*this < b);
    }
    bign operator += (const bign& b) {
        *this = *this + b;
        return *this;
    }
    };
    istream& operator >> (istream &in, bign& x) {
    string s;
    in >> s;
    x = s.c_str();
    return in;
    }
    ostream& operator << (ostream &out, const bign& x) {
    out << x.str();
    return out;
    }
    int main()
    {
        int T,cas;
        cin>>T;cas=1;
        while(T--)
        {
            bign a,b;
            cin >> a >>b ;
            cout<<"Case "<<cas++<<":"<<endl;
            cout << a+b << endl;
        }
        return 0;
    }