loj 10001 种树

*********贪心，把需要的路段终止点排序，然后在每个区间内判断是否已经满足条件，不满足的从区间右端向左端种树。

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
using namespace std;
int i,j,n,h,vis[30005] = {0},ans = 0,tot;
struct node
{
    int b;
    int e;
    int t;
}a[30005];
int cmp(node a,node b)
{
    return a.e < b.e;
}
int main()
{
    scanf("%d",&n);
    scanf("%d",&h);
    for(i = 1;i <= h;i++)
    {
        scanf("%d %d %d",&a[i].b,&a[i].e,&a[i].t);
    }
    sort(a + 1,a + 1 + h,cmp);
    for(i = 1;i <= h;i++)
    {
        tot = 0;
        for(j = a[i].b;j <= a[i].e;j++)
        {
            if(vis[j] == 1)
            {
                tot++;
            }
            if(tot == a[i].t)
            break;
        }
        if(tot < a[i].t)
        {
            for(j = a[i].e;j >= a[i].b;j--)
            {
                if(vis[j] == 0)
                {
                    vis[j] = 1;
                    tot++;
                    ans++;
                }
                if(tot == a[i].t)
                break;
            }
        }
    }
    printf("%d",ans);
    return 0;
}