机试第7章

活动安排（区间贪心）

bool cmp(activity x, activity y)
{
    return x.e < y.e; // 按结束时间排序
}

sort(arr, arr + n, cmp);
int cur = 0, res = 0;
for (int i = 0; i < n; ++i)
    if (cur <= arr[i].s)
    {
        cur = arr[i].e;
        res++;
    }