【HDOJ】1239 Calling Extraterrestrial Intelligence Again

这题wa了很多词，题目本身很简单，把a/b搞反了，半天才检查出来。

 1 #include <stdio.h>

 2 #include <string.h>

 3 #include <math.h>

 4

 5 char isPrime[100001];

 6

 7 int main() {

 8     int i, j, q, p, maxi, maxj, max;

 9     double m, a, b, n, tmp1, tmp2;

10

11     memset(isPrime, 1, sizeof(isPrime));

12     isPrime[0] = isPrime[1] = 0;

13     for (i=2; i<100001; ++i) {

14         if (isPrime[i]) {

15             for (j=i+i; j<100001; j+=i)

16                 isPrime[j] = 0;

17         }

18     }

19

20     while (scanf("%lf %lf %lf", &m, &a, &b) != EOF) {

21         if (m==0.0f && a==0.0f && b==0.0f)

22             break;

23         n = a/b;

24         a = sqrt(m);

25         b = sqrt(m/n);

26         i = (int)floor(a);

27         j = (int)floor(b);

28         max = 0;

29         for (p=j; p>=2; --p) {

30             if ( !isPrime[p] )

31                 continue;

32             if (p*i <= max)

33                 break;

34             for (q=i; q>=2; --q) {

35                 if ( !isPrime[q] )

36                     continue;

37                 tmp1 = p*q;

38                 tmp2 = q*1.0f/p;

39                 if (tmp1<=m && tmp2<=1 && tmp2>=n) {

40                     if (tmp1 > max) {

41                         max = tmp1;

42                         maxj = p;

43                         maxi = q;

44                     }

45                     break;

46                 }

47             }

48         }

49         printf("%d %d\n", maxi, maxj);

50     }

51

52     return 0;

53 }

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