LA3905 流星(Meteor)

　　　　很麻烦的一个题，有很多的技巧可以学到

　　

#include <set>
#include <cstdio>
#include <iostream>
#include <algorithm>
using namespace std;
typedef long long LL;
const int maxn = 100005;
const int INF = 0x3fffffff;
const int k = 2520;//lcm(1,2,..,10);
int w,h;
struct node
{
    int pos;
    int dir;
    friend bool operator <(node a,node b)
    {
        if(a.pos==b.pos)return a.dir>b.dir;
        return a.pos<b.pos;
    }
}e[maxn*2];
void solve(int x,int a,int w,int &l,int &r)
{
    if(a==0){
        if(x<=0 || x>=w)r = l-1;
    }
    else if(a>0){
        l = max(l,-x/a);
        r = min(r,(w-x)/a);
    }
    else {
        l = max(l,(w-x)/a);
        r = min(r,-x/a);
    }
}
int main()
{
//    freopen("in.txt","r",stdin);
    int T;scanf("%d",&T);
    while(T--)
    {
        int n;scanf("%d%d%d",&w,&h,&n);
        w*=k;h*=k;
        int cnt = 0;
        for(int i = 1;i<=n;++i)
        {
            int x,y,a,b;
            scanf("%d%d%d%d",&x,&y,&a,&b);
            int l = 0,r = INF;
            solve(x*k,a,w,l,r);
            solve(y*k,b,h,l,r);
            if(r<=l)continue;
            e[cnt++] = (node){l,0};
            e[cnt++] = (node){r,1};
        }
        sort(e,e+cnt);
        int ans = 0,t = 0;
        for(int i = 0;i<cnt;++i)
        {
            if(e[i].dir)t--;
            else t++;
            ans = max(ans,t);
        }
        printf("%d\n",ans);
    }
    return 0;
}