uva10780Again Prime? No Time.

质因数分解。

 1 //Accepted    0 KB    12 ms

 2 #include <cstdio>

 3 #include <cstring>

 4 #include <cmath>

 5 const int MAXN = 100005;

 6 const int inf = 100000000;

 7 int pri[MAXN];

 8 int cnt;

 9 void prime()

10 {

11     cnt=0;

12     for (int i=2;i<MAXN;i++)

13     {

14         if (!pri[i])

15         {

16             pri[cnt++]=i;

17             if ((long long )i*i<(long long )MAXN)

18             for (int j=i*i;j<MAXN;j+=i)

19             pri[j]=1;

20         }

21     }

22 }

23 int p[100],pNum[100];

24 int num;

25 void getp(int n)

26 {

27     num=0;

28     memset(pNum,0,sizeof(pNum));

29     for (int i=0;i<cnt && pri[i]*pri[i]<=n;i++)

30     {

31         if (n%pri[i]==0)

32         {

33             while (n%pri[i]==0)

34             {

35                 n/=pri[i];

36                 pNum[num]++;

37             }

38             p[num++]=pri[i];

39         }

40     }

41     if (n!=1)

42     {

43         pNum[num]=1;

44         p[num++]=n;

45     }

46 }

47 int getn(int n,int m)

48 {

49     int ans=0;

50     while (n>0)

51     {

52         ans+=n/m;

53         n/=m;

54     }

55     return ans;

56 }

57 int min(int a,int b)

58 {

59     return a>b?b:a;

60 }

61 int slove(int n,int m)

62 {

63     getp(m);

64     int ans=inf;

65     for (int i=0;i<num;i++)

66     {

67         ans=min(ans,getn(n,p[i])/pNum[i]);

68     }

69     return ans;

70 }

71 int n,m;

72 int main()

73 {

74     prime();

75     int T;

76     scanf("%d",&T);

77     for (int t=1;t<=T;t++)

78     {

79         scanf("%d%d",&m,&n);

80         int ans=slove(n,m);

81         printf("Case %d:\n",t);

82         if (ans==0)

83         printf("Impossible to divide\n");

84         else

85         printf("%d\n",ans);

86     }

87     return 0;

88 }