orz jcpwfloi= =
窝本来写了的说。。。被JCPW大爷D惹。。。那就看他的好了！2333
1 /************************************************************** 2 Problem: 3994 3 User: rausen 4 Language: C++ 5 Result: Accepted 6 Time:2664 ms 7 Memory:2320 kb 8 ****************************************************************/ 9 10 #include <cstdio> 11 #include <algorithm> 12 13 using namespace std; 14 typedef long long ll; 15 const int N = 5e4 + 5; 16 const int Maxlen = N * 2 * 7; 17 18 int n, m; 19 int u[N], f[N], d[N], p[N], cnt_p; 20 bool isn_p[N]; 21 ll ans; 22 23 char buf[Maxlen], *c = buf; 24 int Len; 25 26 inline int read() { 27 static int x; 28 x = 0; 29 while (*c < '0' || '9' < *c) ++c; 30 while ('0' <= *c && *c <= '9') 31 x = x * 10 + *c - '0', ++c; 32 return x; 33 } 34 35 inline void get() { 36 int i, j, k; 37 for(u[1] = d[1] = 1, i = 2; i < N; ++i) { 38 if (!isn_p[i]) 39 p[++cnt_p] = i, u[i] = -1, d[i] = 2, f[i] = 1; 40 for (j = 1; j <= cnt_p; ++j) { 41 k = i * p[j]; 42 if (k >= N) break; 43 isn_p[k] = 1; 44 if (i % p[j] == 0) { 45 u[k] = 0, f[k] = f[i] + 1, d[k] = d[i] / f[k] * (f[k] + 1); 46 break; 47 } 48 u[k] = -u[i], d[k] = d[i] * 2, f[k] = 1; 49 } 50 } 51 } 52 53 int main() { 54 Len = fread(c, 1, Maxlen, stdin); 55 buf[Len] = ' '; 56 int T, i, j; 57 T = read(); 58 get(); 59 for (i = 2; i < N; ++i) 60 d[i] += d[i - 1], u[i] += u[i - 1]; 61 while (T--) { 62 n = read(), m = read(); 63 if (n > m) swap(n, m); 64 for (ans = j = 0, i = 1; i <= n; i = j + 1) { 65 j = min(n / (n / i), m / (m / i)); 66 ans += 1ll * (u[j] - u[i - 1]) * d[n / i] * d[m / i]; 67 } 68 printf("%lld ", ans); 69 } 70 return 0; 71 }
(不过呢。。。窝比他快)