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劉汝佳 BigInteger 大數模板

struct BigInteger
{
    static const int BASE = 100000000;
    static const int WIDTH = 8;
    vector<int> s;
    BigInteger(long long num = 0)
    {
        *this = num;
    }
    BigInteger operator=(long long num)
    {
        s.clear();
        do {
            s.push_back(num%BASE);
            num /= BASE;
        } while
(num > 0); return *this; } BigInteger operator=(const string& str) { s.clear(); int x; int len=(str.length() - 1)/WIDTH + 1; for (int i = 0;i < len;i++) { int end = str.length() - i*WIDTH; int start = max(0, end - WIDTH); sscanf
(str.substr(start, end - start).c_str(), "%d", &x); s.push_back(x); } return *this; } BigInteger operator+(const BigInteger& b) const { BigInteger c; c.s.clear(); for (int i = 0,g = 0;;i++) { if (g == 0 && i >= s.size() && i >= b.s.size()) break
; int x = g; if (i < s.size()) x += s[i]; if (i < b.s.size()) x += b.s[i]; c.s.push_back(x%BASE); g = x / BASE; } return c; } BigInteger operator +=(const BigInteger& b) { *this = *this + b; return *this; } bool operator<(const BigInteger& b)const { if (s.size() != b.s.size()) return s.size() < b.s.size(); for (int i = s.size() - 1;i >= 0;i--) if (s[i] != b.s[i]) return s[i] < b.s[i]; return false; } bool operator >(const BigInteger& b)const { return b < *this; } bool operator <=(const BigInteger& b)const { return !(b < *this); } bool operator >=(const BigInteger& b)const { return !(*this < b); } bool operator !=(const BigInteger& b)const { return b < *this || *this < b; } bool operator ==(const BigInteger& b)const { return !(b < *this) && !(*this < b); } }; ostream& operator << (ostream &out, const BigInteger& x) { out << x.s.back(); for (int i = x.s.size() - 2;i >= 0;i--) { char buf[20]; sprintf(buf, "%08d", x.s[i]); for (int j = 0;j < strlen(buf);j++) out << buf[j]; } return out; } istream& operator >> (istream &in, BigInteger& x) { string s; if (!(in >> s)) return in; x = s; return in; }