USACP section1.2 Milking Cows

把所有区间（如果能）合并起来，求最长连续区间长度和最长间隔长度（两个区间之间，如果只有一个区间为0）；

/*
PROG: milk2
LANG: C++
*/

# include <cstdio>
# include <cstdlib>

# define N 5000 + 10

struct val{
    int s, t;
} a[N];

int n;

int cmp(const void *x, const void *y)
{
    val *p = (val*)x;
    val *q = (val*)y;
    if (p->s == q->s) return p->t - q->t;
    return p->s - q->s;
}

int main()
{
    freopen("milk2.in", "r", stdin);
    freopen("milk2.out", "w", stdout);

    scanf("%d", &n);
    for (int i = 0; i < n; ++i)
        scanf("%d%d", &a[i].s, &a[i].t);

    qsort(a, n, sizeof(val), cmp);

    int s = a[0].s, t = a[0].t;
    int M1 = t - s, M2 = 0;
    for (int i = 1; i < n; ++i)
    {
        if (a[i].s <= t && a[i].t > t) t = a[i].t;
        if (a[i].s > t || i == n-1)
        {
            if (t-s > M1) M1 = t - s;
            if (a[i].s-t > M2) M2 = a[i].s - t;
            s = a[i].s, t = a[i].t;
        }
    }

    printf("%d %d\n", M1, M2);

    fclose(stdin);
    fclose(stdout);

    return 0;
}

/**/