POJ 1091 跳蚤

 1 #include <stdio.h>
 2 
 3 long long factor[10000000];
 4 long long  factor_num = 0;
 5 
 6 long long M;
 7 long long N;
 8 
 9 
10 void get_factor(long long num, long long factor[], long long *factor_num)
11 {
12     *factor_num = 0;
13     for (long long i = 2; i * i <= num ; i++)
14     {
15         if (num %i == 0)
16         {
17             *factor_num = (*factor_num) + 1;
18             factor[*factor_num] = i;
19             while( num % i == 0)
20             {
21                 num = num / i;
22             }
23         }
24     }
25     if(num > 1)
26     {
27         *factor_num = (*factor_num) + 1;
28         factor[*factor_num] = num;
29     }
30 }
31 
32 
33 long long pow(long long x, long long index)
34 {
35     long long result = 1;
36     for (long long i = 1; i <= index; i++)
37     {
38         result *= x;
39     }
40     return result;
41 }
42 
43 
44 
45 int main(int argc, char * argv[])
46 {
47 
48     scanf("%lld", &N);
49     scanf("%lld", &M);
50 
51     //printf("N=%d M=%ld\n", N, M);
52 
53     long long total = pow(M, N);
54     get_factor(M,  factor, &factor_num);
55 
56     //printf("total=%ld\n", total);
57 
58 
59     unsigned long long bi_factor_num = (1 << factor_num);
60     //printf("bi_factor_num=%d\n", bi_factor_num);
61 
62 
63     for (unsigned long long i = 1; i < bi_factor_num; i++)
64     {
65         //printf("%d-----\n", i);
66         long long t = 0;
67         long long facts = 1;
68         long long  k = 1;
69         for (unsigned long long j = i;  j >=  1; j = j >> 1)
70         {
71             if (j & 1)
72             {
73                 t++;
74                 facts *= factor[k];
75             }
76             k++;
77             //printf("j =%d\n", j);
78             //printf("k =%d\n", k);
79         }
80             //printf("facts = %d  %d %d\n", facts, t, pow(M/facts, N));
81             if (t % 2 == 1)
82             {
83                 total = total - pow(M/facts, N);
84             }
85             else if (t % 2 == 0)
86             {
87                 total = total + pow(M/facts, N);
88             }
89 
90     }
91 
92     //printf("Done\n");
93     printf("%lld\n", total);
94     return 0;
95 }