usaco-2.1-frac1-pass

这个最简递增分数题关键在于最简，如果知道这个方法，此题易解。呵呵，一次性通过。

/*
ID: qq104801
LANG: C++
TASK: frac1
*/

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
#include <cstdlib>
#include <cmath>

using namespace std;

int n;
struct frac
{
    int up;
    int down;
    bool operator < (const frac &b)const{
       return up*b.down < down*b.up; }
};

bool cmp(const frac &a,const frac &b)
{
    return a.up*b.down < b.down*b.up;
}

int isstupid(int up,int down)
{
    int t;
    if (up==1)return 1;
    if(down%up==0)return 0;
    while(down%up!=0)
    {
        t=up;up=down%up;down=t;
    }
    if(up>1)return 0;
    else return 1;
}

void test()
{
    freopen("frac1.in","r",stdin);
    freopen("frac1.out","w",stdout);
    cin >> n;
    //cout<<n<<endl;
    cout<<"0/1"<<endl;
    vector<frac> v;
    int i,j,k;
    frac f;
    for(i=2;i<=n;i++)
        for(j=1;j<=i;j++)
        {
            if(isstupid(j,i))
            {
                f.up=j;f.down=i;
                v.push_back(f);
                //cout<<f.up<<"/"<<f.down<<endl;
            }
        }
    sort(v.begin(),v.end());
    //cout<<endl;
    vector<frac>::iterator it;
    for(it=v.begin();it!=v.end();it++)
        cout<<it->up<<"/"<<it->down<<endl;

    cout<<"1/1"<<endl;
}

int main ()
{
    test();
    return 0;
}

测试结果：

USER: cn tom [qq104801]
TASK: frac1
LANG: C++

Compiling...
Compile: OK

Executing...
   Test 1: TEST OK [0.008 secs, 3376 KB]
   Test 2: TEST OK [0.011 secs, 3508 KB]
   Test 3: TEST OK [0.008 secs, 3508 KB]
   Test 4: TEST OK [0.008 secs, 3508 KB]
   Test 5: TEST OK [0.008 secs, 3508 KB]
   Test 6: TEST OK [0.011 secs, 3508 KB]
   Test 7: TEST OK [0.014 secs, 3508 KB]
   Test 8: TEST OK [0.038 secs, 3508 KB]
   Test 9: TEST OK [0.070 secs, 3508 KB]
   Test 10: TEST OK [0.097 secs, 3508 KB]
   Test 11: TEST OK [0.329 secs, 3508 KB]

All tests OK.

YOUR PROGRAM (‘frac1‘) WORKED FIRST TIME! That‘s fantastic -- and a rare thing. Please accept these special automated congratulations.

Here are the test data inputs:

------- test 1 ----
1
------- test 2 ----
2
------- test 3 ----
4
------- test 4 ----
7
------- test 5 ----
10
------- test 6 ----
15
------- test 7 ----
24
------- test 8 ----
50
------- test 9 ----
75
------- test 10 ----
100
------- test 11 ----
160

Keep up the good work!
Thanks for your submission!