大数模板！

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <cstdlib>
  4 #include <cstring>
  5 #define UNIT 10
  6 
  7 using namespace std;
  8 
  9 struct Bignum
 10 {
 11     int val[105];
 12     int len;
 13 
 14     Bignum ()
 15     {
 16         memset (val, 0, sizeof(val));
 17         len = 1;
 18     }
 19 
 20     Bignum operator = (const int &a)
 21     {
 22         int t, p = a;
 23         len = 0;
 24         while (p >= UNIT)
 25         {
 26             t = p - (p/UNIT)*UNIT;
 27             p = p / UNIT;
 28             val[len++] = t;
 29         }
 30         val[len++] = p;
 31         return *this;
 32     }
 33 
 34     Bignum operator + (const Bignum &a) const//大数加大数
 35     {
 36         Bignum x = a;
 37         int L;
 38         L = a.len > len ? a.len : len;
 39         for (int i = 0; i < L; ++i)
 40         {
 41             x.val[i] += val[i];
 42             if (x.val[i] >= UNIT)
 43             {
 44                 x.val[i+1]++;
 45                 x.val[i] -= UNIT;
 46             }
 47         }
 48         if (x.val[L] != 0)
 49             x.len = L+1;
 50         else
 51             x.len = L;
 52         return x;
 53     }
 54 
 55     Bignum operator - (const Bignum &a) const
 56     {
 57         bool flag;
 58         Bignum x1, x2;
 59         if (*this > a)
 60         {
 61             x1 = *this;
 62             x2 = a;
 63             flag = 0;
 64         }
 65         else
 66         {
 67             x1 = a;
 68             x2 = *this;
 69             flag = 1;
 70         }
 71         int j, L = x1.len;
 72         for (int i = 0; i < L; ++i)
 73         {
 74             if (x1.val[i] < x2.val[i])
 75             {
 76                 j = i+1;
 77                 while (x1.val[j] == 0)
 78                     j++;
 79                 x1.val[j--]--;
 80                 while (j > i)
 81                     x1.val[j--] += UNIT-1;
 82                 x1.val[i] += UNIT-x2.val[i];
 83             }
 84             else
 85                 x1.val[i] -= x2.val[i];
 86         }
 87         while (x1.val[x1.len-1] == 0 && x1.len > 1)
 88             x1.len--;
 89         if (flag)
 90             x1.val[x1.len-1] = -x1.val[x1.len-1];
 91         return x1;
 92     }
 93 
 94     Bignum operator * (const Bignum &a) const//大数乘大数
 95     {
 96         Bignum x;
 97         int i, j, up;
 98         int x1, x2;
 99         for (i = 0; i < len; i++)
100         {
101             up = 0;
102             for (j = 0; j < a.len; j++)
103             {
104                 x1 = val[i]*a.val[j] + x.val[i+j] + up;
105                 if (x1 >= UNIT)
106                 {
107                     x2 = x1 - x1/UNIT*UNIT;
108                     up = x1 / UNIT;
109                     x.val[i+j] = x2;
110                 }
111                 else
112                 {
113                     up = 0;
114                     x.val[i+j] = x1;
115                 }
116             }
117             if (up != 0)
118                 x.val[i+j] = up;
119         }
120         x.len = i + j;
121         while (x.val[x.len-1] == 0 && x.len > 1)
122             x.len--;
123         return x;
124     }
125 
126     Bignum operator / (const int &a) const//大数除小数
127     {
128         Bignum x;
129         int down = 0;
130         for (int i = len-1; i >= 0; --i)
131         {
132             x.val[i] = (val[i]+down*UNIT) / a;
133             down = val[i] + down*UNIT - x.val[i]*a;
134         }
135         x.len = len;
136         while (x.val[x.len-1] == 0 && x.len > 1)
137             x.len--;
138         return x;
139     }
140 
141     int operator % (const int &a) const//大数模小数
142     {
143         int x = 0;
144         for (int i = len-1; i >= 0; --i)
145             x = ((x*UNIT)%a+val[i]) % a;
146         return x;
147     }
148 
149     Bignum operator ^ (const int &a) const
150     {
151         Bignum p, x;
152         x.val[0] = 1;
153         if(a < 0)
154             exit(-1);
155         if(a == 0)
156             return x;
157         if(a == 1)
158             return *this;
159         int n = a, i;
160         while(n > 1)
161         {
162             p = *this;
163             for(i = 1; (i<<1) <= n; i<<=1)
164                 p = p * p;
165             n -= i;
166             x = x * p;
167             if(n == 1)
168                 x = x * (*this);
169         }
170         return x;
171     }
172 
173     bool operator > (const Bignum &a) const
174     {
175         int now;
176         if (len > a.len)
177             return true;
178         else if (len == a.len)
179         {
180             now = len - 1;
181             while (val[now] == a.val[now] && now >= 0)
182                 now--;
183             if(now >= 0 && val[now] > a.val[now])
184                 return true;
185             else
186                 return false;
187         }
188         else
189             return false;
190     }
191 };
192 
193 int main()
194 {
195     /*f[0] = 1;
196     for(int i=1;i<=100;i++)
197     f[i]=f[i-1]*(4*i-2)/(i+1);//卡特兰数递推式
198     int n;
199     while(scanf("%d",&n)==1)
200     {
201         if(n==-1)
202             break;
203         f[n].print();
204     }*/
205     return 0;
206 }
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