C - Aladdin and the Flying Carpet

Posted 2020-11-19 jaydenouyang

 1 #include<bitset>
 2 #include<map>
 3 #include<vector>
 4 #include<cstdio>
 5 #include<iostream>
 6 #include<cstring>
 7 #include<string>
 8 #include<algorithm>
 9 #include<cmath>
10 #include<stack>
11 #include<queue>
12 #include<set>
13 #define inf 0x3f3f3f3f
14 #define mem(a,x) memset(a,x,sizeof(a))
15 
16 using namespace std;
17 typedef long long ll;
18 
19 //输入挂
20 inline ll in()
21 {
22     ll res=0;char c;
23     while((c=getchar())<‘0‘ || c>‘9‘);
24     while(c>=‘0‘ && c<=‘9‘)res=res*10+c-‘0‘,c=getchar();
25     return res;
26 }
27 
28 const int N=1000010;
29 ll prime[79000];
30 int p;
31 bitset<N> vis;
32 
33 void init()
34 {
35     for(int i=2;i<N;i++)
36     {
37         if(!vis[i])
38         {
39             prime[p++]=i;
40             for(int j=i+i;j<N;j+=i)
41             {
42                 vis[j]=1;
43             }
44         }
45     }
46 }
47 int main()
48 {
49     int T = in();
50     int ii = 1;
51     init();
52     while(T--)
53     {
54         ll area = in(),min_side = in();
55         if(min_side >= sqrt(area)){
56             printf("Case %d: %d
",ii++,0);
57             continue;
58         }
59         ll tmp = area;
60         int ans = 1;
61         for(int i = 0;i < p && prime[i]*prime[i] <= area;i++)
62         {
63             int cnt = 0;
64             while(area%prime[i] == 0)
65             {
66                 area /= prime[i];
67                 cnt++;
68             }
69             ans *= (cnt+1);
70         }
71         if(area != 1) ans <<= 1;
72         ans >>= 1;  //因数的个数除以二就是组数，同时排除了平方根
73         for(int i = 1;i < min_side;i++) 
74             if(tmp%i == 0) ans--; //min_side此时是小于sqrt（area）的
75         printf("Case %d: %d
",ii++,ans);
76     }
77     return 0;
78 }