Selecting courses (hdu 3697 greedy

Topic links: http://acm.hdu.edu.cn/showproblem.php?pid=3697

 Because the election once every 5 minutes so you can enumerate 0-4 5-1000 can be added to obtain a 0-4 plus 55

Then is the topic that can be started when non-integer point that we enumerate 0.0001,1.0001,2.0001,3.0001,4.0001

So definitely better than enumeration 0-4 can choose to be more

so 我们for（i=0 to 4）

j = i to 1000 plus 5 per

A time period from the start if the <= j and end time> j would be chosen (assuming now because i is from 0 0.0001 actually representative of the start time so that time is 0, but may be selected on the end of the time must be> 0)

 

Code;

#include<bits/stdc++.h>
using namespace std;
struct node
{
    int s,t;
}a[305];
bool cmp(node x,node y)
{
    if(x.t!=y.t)return x.t<y.t;
        return x.s<y.s;
}
int main()
{
    int n,i,j;
    while(scanf("%d",&n),n)
    {
        for(i=0;i<n;i++)
        {
            scanf("%d%d",&a[i].s,&a[i].t);
        }
        sort(a,a+n,cmp);
        int maxx=0;
        for(i=0;i<=4;i++)//假设从0.001开始 即i=0
        {
            int visit[305];
            int ans=0;
            memset(visit,0,sizeof(visit));
            for(j=i;j<=1000;j+=5)
            {
                for(int k=0 ; k <n-; k ++ ) 
                { 
                    IF (Visit [k] == 0 && a [k] .s <&& j = a [k] .T> j) // this is a [k] can be equal to j .s (j i come from each addition. 5) 
                    { 
                        Visit [K] = . 1 ; 
                        ANS ++ ;
                         BREAK ; 
                    } 
                } 
            } 
            Maxx = max (Maxx, ANS); 
        } 
        COUT << Maxx << endl; 
    } 
    return  0 ; 
}

View Code