UVa 10539 (筛素数、二分查找) Almost Prime Numbers

 1 #include <cstdio>
 2 #include <cmath>
 3 #include <algorithm>
 4 
 5 typedef long long LL;
 6 
 7 const int maxn = 1000000;
 8 const int maxp = 80000;
 9 
10 bool vis[maxn + 10];
11 int prime[maxp], cntp = 0;
12 LL a[maxn], cnt = 1;
13 
14 void Init()
15 {
16     int m = 1000;
17     for(int i = 2; i <= m; ++i) if(!vis[i])
18         for(int j = i * i; j <= maxn; j += i) vis[j] = true;
19     for(int i = 2; i <= maxn; ++i) if(!vis[i]) prime[cntp++] = i;
20 
21     for(int i = 0; i < cntp; ++i)
22     {
23         LL temp = (LL)prime[i] * prime[i];
24         while(temp <= 1000000000000LL)
25         {
26             a[cnt++] = temp;
27             temp *= prime[i];
28         }
29     }
30     std::sort(a, a + cnt);
31 }
32 
33 int binary_search(LL n)
34 {
35     LL L = 0, R = cnt;
36     while(L < R)
37     {
38         LL mid = ((L + R + 1) >> 1);
39         if(a[mid] <= n) L = mid;
40         else R = mid - 1;
41     }
42     return L;
43 }
44 
45 int main()
46 {
47     Init();
48     int T;
49     scanf("%d", &T);
50     while(T--)
51     {
52         LL hehe, haha;
53         scanf("%lld%lld", &hehe, &haha);
54         int t = binary_search(hehe), k = binary_search(haha);
55         int ans = k - t;
56         if(a[t] == hehe) ans++;
57         printf("%d\n", ans);
58     }
59 
60     return 0;
61 }