[Swust OJ 491]--分数的位置(简单版)

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <cstdio>
 4 #define maxn 1000010
 5 using namespace std;
 6 struct node{
 7     int x, y;
 8     bool operator<(const node &tmp)const{
 9         if (x != tmp.x)
10             return x*tmp.y < y*tmp.x;
11         return y > tmp.y;
12     }
13 }a[maxn];
14 int gcd(int a, int b){
15     return !b ? a : gcd(b, a%b);
16 }
17 int main(){
18     int n, m;
19     while (~scanf("%d%d", &n, &m)){
20         int pos = 0;
21         //i代表分母,j代表分子
22         for (int i = 1; i <= n; i++){
23             for (int j = 1; j < i; j++){
24                 if (i == 1 && j == 1)
25                     continue;
26                 if (gcd(j, i) == 1){
27                     a[pos].x = j;
28                     a[pos++].y = i;//  x/y
29                 }
30             }
31         }
32         sort(a, a + pos);
33         printf("%d/%d\n", a[m - 1].x, a[m - 1].y);
34     }
35     return 0;
36 }
37 
38 //排序也可以这么单独写,看个人习惯
39 /*int cmp(node a, node b){
40     if (a.x == b.x)
41         return a.y > b.y;
42     return a.x*b.y < a.y*b.x;
43 }*/