题解：
题意：旅店的租房时间，有一个开始时间，一个结束时间，问最多能安排多少个旅客，两个时间段不能重叠，对结束时间排序，贪心就好了，第一段时间一定要选。
代码
#include<stdio.h>
#include<math.h>
#include<string.h>
#include<stack>
#include<queue>
#include<vector>
#include<iostream>
#include<algorithm>
#define MAXN 501000
#define LL long long
#define ll __int64
#define INF 0xfffffff
#define mem(x) memset(x,0,sizeof(x))
#define PI acos(-1)
using namespace std;
struct s
{
ll begin;
ll end;
}a[MAXN];
bool cmp(s a,s b)
{
if(a.end==b.end)
return a.begin<b.begin;
return a.end<b.end;
}
int main()
{
int t,n,m,i,j,k;
int cas=0;
while(scanf("%d",&n)!=EOF)
{
for(i=0;i<n;i++)
scanf("%I64d%I64d",&a[i].begin,&a[i].end);
sort(a,a+n,cmp);
ll k=a[0].end;
int ans=1;
for(i=1;i<n;i++)
{
if(a[i].begin>k)
{
ans++;
k=a[i].end;
}
}
printf("%d\n",ans);
}
return 0;
}题目
B. Restaurant
time limit per test 4 seconds
memory limit per test 256 megabytes
input standard input
output standard output
A restaurant received n orders for the rental. Each rental order reserve the restaurant for a continuous period of time, the i-th order is characterized by two time values — the start time li and the finish time ri (li ≤ ri).
Restaurant management can accept and reject orders. What is the maximal number of orders the restaurant can accept?
No two accepted orders can intersect, i.e. they can’t share even a moment of time. If one order ends in the moment other starts, they can’t be accepted both.
Input
The first line contains integer number n (1 ≤ n ≤ 5·105) — number of orders. The following n lines contain integer values li and ri each (1 ≤ li ≤ ri ≤ 109).
Output
Print the maximal number of orders that can be accepted.
Sample test(s)
input
2
7 11
4 7
output
1
input
5
1 2
2 3
3 4
4 5
5 6
output
3
input
6
4 8
1 5
4 7
2 5
1 3
6 8
output
2
