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。
1 #include <cstdio> 2 #include <algorithm> 3 #include <climits> 4 using namespace std; 5 #define MAXN 5000+10 6 7 struct Interval 8 { 9 int l, r; 10 }; 11 12 Interval interval[MAXN]; 13 14 bool cmp(const Interval a, const Interval b) 15 { 16 if (a.l != b.l) return a.l < b.l; 17 return a.r < b.r; 18 } 19 20 int main() 21 { 22 #ifdef LOCAL 23 freopen("in", "r", stdin); 24 #endif 25 int N; 26 scanf("%d", &N); 27 while (N--) 28 { 29 int n; 30 scanf("%d", &n); 31 for (int i = 0; i < n; i++) 32 scanf("%d%d", &interval[i].l, &interval[i].r); 33 sort(interval, interval+n, cmp); 34 int start, end = 0; 35 int ans = 0; 36 int p = 0; // p points to the interval which is being considered 37 // find the maximum interval starting with the same start 38 while (end < n) 39 { 40 start = end + 1; 41 int upper = INT_MIN; 42 while (p < n && interval[p].l <= start) 43 { 44 upper = max(upper, interval[p].r); 45 p++; 46 } 47 ans++; 48 end = upper; 49 } 50 printf("%d ", ans); 51 } 52 return 0; 53 }