usaco2.11Ordered Fractions

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 1 /*

 2    ID: your_id_here

 3    PROG: frac1

 4    LANG: C++

 5  */

 6 #include <iostream>

 7 #include<cstdio>

 8 #include<cstring>

 9 #include<algorithm>

10 using namespace std;

11 int w[201][201];

12 struct node

13 {

14     int x,y;

15     double s;

16 }q[20001];

17 void gcd(int x,int y)

18 {

19     int i;

20     int tx = x,ty = y;

21     for(i = ty; i >= 2 ; i--)

22     {

23         if(y%i==0&&x%i==0)

24         {

25             y = y/i;

26             x = x/i;

27         }

28     }

29     w[x][y] = 1;

30 }

31 bool cmp(node x,node y)

32 {

33     return x.s<y.s;

34 }

35 int main()

36 {

37     freopen("frac1.in","r",stdin);

38     freopen("frac1.out","w",stdout);

39     int i,j,k,n,g=0;

40     cin>>n;

41     for(i = 2; i <= n ; i++)

42     for(j = 1; j < i ;j++)

43     {

44         gcd(i,j);

45     }

46     for(i = 1; i <= n ; i++)

47     for(j = 1; j <= n ; j++)

48     {

49         if(w[i][j])

50         {

51             g++;

52             q[g].x = i;

53             q[g].y = j;

54             q[g].s = j*1.0/(i*1.0);

55         }

56     }

57     sort(q+1,q+g+1,cmp);

58     cout<<"0/1\n";

59     for(i = 1; i <= g ; i++)

60     printf("%d/%d\n",q[i].y,q[i].x);

61     cout<<"1/1\n";

62     fclose(stdin);

63     fclose(stdout);

64     return 0;

65 }