大整数类（模板）

Posted 2021-01-06 lfri

  1 const int maxn = 5000 + 10;  //最大位数
  2 
  3 struct BigInteger
  4 {
  5     int len, s[maxn];
  6     BigInteger()
  7     {
  8         memset(s, 0, sizeof(s));
  9         len = 1;
 10     }
 11     BigInteger(int num) { *this = num; }
 12     BigInteger(const char *num) { *this = num; }
 13     void clean() { while (len > 1 && !s[len - 1])len--; }
 14     BigInteger operator = (const int num)
 15     {
 16         char s[maxn];
 17         sprintf(s, "%d", num);
 18         *this = s;
 19         return *this;
 20     }
 21     BigInteger operator = (const char *num)
 22     {
 23         len = strlen(num);
 24         for (int i = 0; i < len; i++)s[i] = num[len - i - 1] - ‘0‘;
 25         return *this;
 26     }
 27     BigInteger operator + (const BigInteger& b)
 28     {
 29         BigInteger c;
 30         c.len = 0;
 31         for (int i = 0, g = 0; g || i < max(len, b.len); i++)
 32         {
 33             int x = g;
 34             if (i < b.len)x += b.s[i];
 35             if (i < len)x += s[i];
 36             c.s[c.len++] = x % 10;
 37             g = x / 10;
 38         }
 39         return c;
 40     }
 41     BigInteger operator - (const BigInteger& b)
 42     {
 43         BigInteger c;
 44         c.len = 0;
 45         for (int i = 0, g = 0; i < len; i++)
 46         {
 47             int x = s[i] - g;
 48             if (i < b.len)x -= b.s[i];
 49             if (x >= 0)g = 0;
 50             else { g = 1; x += 10; }
 51             c.s[c.len++] = x;
 52         }
 53         c.clean();
 54         return c;
 55     }
 56     BigInteger operator * (const BigInteger& b)
 57     {
 58         BigInteger c;
 59         c.len = len + b.len;
 60         for (int i = 0; i < len; i++)
 61         {
 62             for (int j = 0; j < b.len; j++)
 63             {
 64                 c.s[i + j] += s[i] * b.s[j];
 65             }
 66         }
 67         for (int i = 0; i < c.len; i++)
 68         {
 69             c.s[i + 1] += c.s[i] / 10;
 70             c.s[i] %= 10;
 71         }
 72         c.clean();
 73         return c;
 74     }
 75     BigInteger operator * (const int& b)
 76     {
 77         BigInteger c;
 78         c.len = 0;
 79         for (int i = 0, g = 0; g || i < len; i++)
 80         {
 81             int x;
 82             if (i < len)x = s[i] * b + g;
 83             else x = g;
 84             c.s[c.len++] = x % 10;
 85             g = x / 10;
 86         }
 87         return c;
 88     }
 89     BigInteger operator / (const BigInteger& b)
 90     {
 91         BigInteger c, f = 0;
 92         for (int i = len - 1; i >= 0; i--)
 93         {
 94             f = f * 10;
 95             f.s[0] = s[i];
 96             while (f >= b)
 97             {
 98                 f = f - b;
 99                 c.s[i]++;
100             }
101         }
102         c.len = len;
103         c.clean();
104         return c;
105     }
106     BigInteger operator / (const int& b)
107     {
108         BigInteger c, d = *this;
109         c.len = len;
110         for (int i = len - 1, g = 0; i >= 0; i--)
111         {
112             d.s[i] += g * 10;
113             c.s[i] = d.s[i] / b;
114             g = d.s[i] % b;
115         }
116         c.clean();
117         return c;
118     }
119     BigInteger operator % (const BigInteger& b)
120     {
121         BigInteger c = *this / b;
122         c = *this - c * b;
123         return c;
124     }
125     BigInteger operator += (const BigInteger& b)
126     {
127         *this = *this + b; return *this;
128     }
129     BigInteger operator -= (const BigInteger& b)
130     {
131         *this = *this - b; return *this;
132     }
133     BigInteger operator *= (const BigInteger& b)
134     {
135         *this = *this*b; return *this;
136     }
137     BigInteger operator /= (const BigInteger& b)
138     {
139         *this = *this / b; return *this;
140     }
141     BigInteger operator *= (const int& b)
142     {
143         *this = *this*b; return *this;
144     }
145     BigInteger operator /= (const int& b)
146     {
147         *this = *this / b; return *this;
148     }
149     BigInteger operator %= (const BigInteger& b)
150     {
151         *this = *this%b; return *this;
152     }
153     bool operator < (const BigInteger& b)
154     {
155         if (b.len != len)return len < b.len;
156         for (int i = len - 1; i >= 0; i--)
157         {
158             if (s[i] != b.s[i])return s[i] < b.s[i];
159         }
160         return 0;
161     }
162     bool operator > (const BigInteger& b)
163     {
164         if (b.len != len)return len > b.len;
165         for (int i = len - 1; i >= 0; i--)
166         {
167             if (s[i] != b.s[i])return s[i] > b.s[i];
168         }
169         return 0;
170     }
171     bool operator == (const BigInteger& b)
172     {
173         return !(*this > b) && !(*this < b);
174     }
175     bool operator <= (const BigInteger& b)
176     {
177         return !(*this > b);
178     }
179     bool operator >= (const BigInteger& b)
180     {
181         return !(*this < b);
182     }
183     bool operator != (const BigInteger& b)
184     {
185         return !(*this == b);
186     }
187     string str() const
188     {
189         string res;
190         for (int i = 0; i < len; i++)
191             res = char(s[i] + ‘0‘) + res;
192         return res;
193     }
194 };
195 istream& operator >> (istream&in, BigInteger &x)
196 {
197     string s;
198     in >> s;
199     x = s.c_str();
200     return in;
201 }
202 ostream& operator << (ostream&out, BigInteger x)
203 {
204     out << x.str();
205     return out;
206 }