HDU 5742

题意：
    给出序列 a[] 的其中几项 ，已知序列满足非减，并且 0 <= ai <= 100， 问 (a1 + a2) / ( ∑ai)最大可能是多少
    
分析：
    保证 a1,a2尽可能大， 其余尽可能小即可

#include <iostream>
#include <cstring>
using namespace std;
int t, n, m;
int a[105];
int GCD(int a, int b)
{
    return b == 0? a : GCD(b, a % b);
}
int main()
{
    scanf("%d", &t);
    while (t--)
    {
        memset(a, -1, sizeof(a));
        scanf("%d%d", &n, &m);
        if (m == 0 || n == 2)
        {
            puts("1/1"); continue;
        } 
        for (int i = 1; i <= m; i++)
        {
            int x, y;
            scanf("%d%d", &x, &y);
            a[x] = y;
        }
        int Min=0;
        for (int i = n; i > 2; i--)
        {
            if (a[i] == -1) a[i] = Min;
            else Min = a[i];
        }
        if (a[1] == -1) a[1] = 100;
        if (a[2] == -1) a[2] = a[1];
        int tu = a[1] + a[2], td = 0;
        for (int i = 1; i <= n; i++) td += a[i]; 
        int gcd = GCD(tu, td);
        tu /= gcd;
        td /= gcd;
        printf("%d/%d
", tu, td);
    }
}