8.5-Day1T3--Asm.Def 的一秒

题目大意

略...

（吐槽这题面...让我毫无阅读兴趣）

题解

首先要求出在以两条斜线为新坐标轴下，每个点的坐标

那么....按x先排序

再求y的最长上升子序列

复杂度O(nlogn)吧

记得开longlong

#include<cstdio>
#include<algorithm>
#include<cstring>
#define ll long long
using namespace std;
inline ll read()
{
    ll sum = ,p = ;
    char ch = getchar();
    while(ch < '' || ch > '')
    {
        if(ch == '-')
            p = -;
        ch = getchar();
    }
    while(ch >= '' && ch <= '')
    {
        (sum *= ) += ch - '';
        ch = getchar();
    }
    return sum * p;
}
const int maxn = ;
ll n,a,b,c,d,f[maxn];
struct pot
{
    ll x,y;
}p[maxn];
bool cmp(pot a,pot b){return a.x < b.x;}
ll lis()
{
    ll len = ;
    for(int i = ;i <= n;i++)
        if(p[i].x >  && p[i].y > )
        {
            if(p[i].y > f[len])
                f[++len] = p[i].y;
            else
            if(p[i].y< f[])
                f[] = p[i].y;
            else
                f[lower_bound(f + ,f + len + ,p[i].y) - f] = p[i].y;
        }
        return len;
}
int main()
{
    n = read();
    a = read(),b = read(),c = read(),d = read();
    for(int i = ;i <= n;i++)
    {
        int x = read(),y = read();
        p[i].x = c * x - d * y;
        p[i].y = b * y - a * x;
    }
    sort(p+,p + n + ,cmp);
    printf("%lld",lis());
    return ;
}