区间选点（贪心）

#include <iostream>
#include <algorithm>
using namespace std;
const int N = 100010;
int n;
struct Range
{
    int l, r;
}range[N];
bool cmp(Range a,Range b)//在结构体外面，千万不能放在结构体里面
{                        //构造升序排列
    return a.r<b.r;
}
int main()
{
    scanf("%d", &n);
    for (int i = 0; i < n; i ++ ) scanf("%d%d", &range[i].l, &range[i].r);
                                    //还可以写成scanf("%d%d",&l,&r);
    sort(range, range + n, cmp);     //range[i]={l,r};
    int num = 0, ed = -2e9;
    for (int i = 0; i < n; i ++ )
        if (range[i].l > ed)
        {
            num ++ ;
            ed = range[i].r;
        }
    printf("%d\n", num);
    return 0;
}