hdu 1133 Buy the Ticket（大数运算）

ans = (m+n)!*(m-n+1)/(m+1).

大数乘小数，大数除小数。

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 1 /*

 2 Author:Zhaofa Fang

 3 Lang:C++

 4 */

 5 #include <cstdio>

 6 #include <cstdlib>

 7 #include <sstream>

 8 #include <iostream>

 9 #include <cmath>

10 #include <cstring>

11 #include <algorithm>

12 #include <string>

13 #include <utility>

14 #include <vector>

15 #include <queue>

16 #include <stack>

17 #include <map>

18 #include <set>

19 using namespace std;

20 

21 typedef long long ll;

22 #define DEBUG(x) cout<< #x << ':' << x << endl

23 #define REP(i,n) for(int i=0;i < (n);i++)

24 #define FOR(i,s,t) for(int i = (s);i <= (t);i++)

25 #define FORD(i,s,t) for(int i = (s);i >= (t);i--)

26 #define PII pair<int,int>

27 #define PB push_back

28 #define MP make_pair

29 #define ft first

30 #define sd second

31 #define lowbit(x) (x&(-x))

32 #define INF (1<<30)

33 

34 int p[1000],q[1000];

35 

36 void print(int a[])

37 {

38     int k = 999;

39     while(k>=0 && !a[k])k--;

40     FORD(i,k,0)printf("%d",a[i]);

41     puts("");

42 }

43 void pro_Aa(int a[],int b)

44 {

45     int c[1000]={0};

46     int e = 0;

47     int k = 0;

48     while(b)

49     {

50         for(int j=0;j+k<1000;j++)

51         {

52             int tmp = a[j] * (b%10);

53             int tmp1 = tmp + c[j+k] + e;

54             c[j+k] = (tmp1)%10;

55             e = (tmp1)/10;

56         }

57         b /= 10;k++;

58     }

59     REP(j,1000)a[j]=c[j];

60 }

61 void div(int a[],int b)

62 {

63     int k = 999;

64     while(k>=0 && !a[k])k--;

65     int e = 0;

66     FORD(i,k,0)

67     {

68         int tmp = e*10 + a[i];

69         a[i] = tmp/b;

70         e = tmp%b;

71     }

72 }

73 int main()

74 {

75     //freopen("in","r",stdin);

76     //freopen("output.txt","w",stdout);

77     int m,n;

78     int cas = 0;

79     while(~scanf("%d%d",&m,&n))

80     {

81         if(!m && !n)break;

82         printf("Test #%d:\n",++cas);

83         if(m < n)

84         {

85             puts("0");

86             continue;

87         }

88         memset(p,0,sizeof(p));

89         p[0] = 1;

90         FORD(i,m+n,2)pro_Aa(p,i);

91         pro_Aa(p,m-n+1);

92         div(p,m+1);

93         print(p);

94     }

95     return 0;

96 }