CSU Scientific Conference

贪心：

#include<stdio.h>
#include<stdlib.h>
#define MAXN 100000 + 100

int Ts[MAXN], Te[MAXN], r[MAXN], n, num;

int cmp(const void *_p, const void *_q)
{
    int *p = (int *)_p;
    int *q = (int *)_q;
    return Te[*p] - Te[*q];
}

void init()
{
    while(~scanf("%d",&n))
    {
        for(int i = 0; i < n; i ++)
        {
            scanf("%d%d",&Ts[i],&Te[i]);
            r[i] = i;
        }
        qsort(r,n,sizeof(r[0]),cmp);
        num = 1;
        int t = 0;
        for(int i = 1; i < n; i ++)
        {
            if(Ts[r[i]]>Te[r[t]]) 
            {
                num ++;
                t = i;
            }
        }
        printf("%d\n",num);
    }
}
int main()
{
    init();
    return 0;
}