ZOJ 3197

　　题目大意：也是区间覆盖问题，是关于书籍查询的，和UVa 10020差不多，不过比那个简单，不用判断是否能覆盖，直接输出最小个数就行了。

#include <cstdio>
#include <algorithm>
#include <climits>
using namespace std;
#define MAXN 5000+10

struct Interval
{
    int l, r;
};

Interval interval[MAXN];

bool cmp(const Interval a, const Interval b)
{
    if (a.l != b.l)   return a.l < b.l;
    return a.r < b.r;
}

int main()
{
#ifdef LOCAL
    freopen("in", "r", stdin);
#endif
    int N;
    scanf("%d", &N);
    while (N--)
    {
        int n;
        scanf("%d", &n);
        for (int i = 0; i < n; i++)
            scanf("%d%d", &interval[i].l, &interval[i].r);
        sort(interval, interval+n, cmp);
        int start, end = 0;
        int ans = 0;
        int p = 0;  // p points to the interval which is being considered
        // find the maximum interval starting with the same start
        while (end < n)
        {
            start = end + 1;
            int upper = INT_MIN;
            while (p < n && interval[p].l <= start)
            {
                upper = max(upper, interval[p].r);
                p++;
            }
            ans++;
            end = upper;
        }
        printf("%d
", ans);
    }
    return 0;
}