poj 1091 解多元不定方程

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #include <stack>
 5 #include <queue>
 6 #include <map>
 7 #include <algorithm>
 8 #include <vector>
 9 #include <cmath>
10 
11 using namespace std;
12 
13 const int maxn = 1000005;
14 
15 typedef long long LL;
16 
17 int fac[1005];
18 int t;
19 
20 void divide(int m)
21 {
22     int i;
23     t = 0;
24     int k = (int)sqrt(m);
25     for(int i=2;i<=k;i++){
26         if(m%i == 0){
27             t++;
28             fac[t] = i;
29             while(m%i == 0)
30             m /= i;
31         }
32     }
33     if(m != 1){
34         t++;
35         fac[t] = m;
36     }
37 }
38 LL quick_multi(LL a,LL b)
39 {
40     LL ans = 1;
41     while(b){
42         ans *= a;
43         b--;
44     }
45     return ans;
46 }
47 
48 LL ans,temp;
49 int a[100],m,n;
50 
51 void dfs(int b,int ct,int c) //有c个公因子
52 {
53     int i,x;
54     if(ct == c){
55         x = m;
56         for(i=1;i<=c;i++){
57             x /= a[i];
58         }
59         temp += quick_multi(x,n);
60         return ;
61     }
62     for(i = b+1;i<=t;i++){
63         a[ct+1] = fac[i];
64         dfs(i,ct+1,c);
65     }
66 }
67 int main()
68 {
69     int i;
70     while(scanf("%d%d",&n,&m)!=EOF){
71         ans = t = 0;
72         divide(m);
73         for(int i=1;i<=t;i++){
74             temp = 0;
75             dfs(0,0,i);
76             if(i&1){
77                 ans += temp;
78             }
79             else
80                 ans -= temp;
81         }
82         ans = quick_multi(m,n) - ans;
83         printf("%lld\n",ans);
84     }
85 
86     return 0;
87 }