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 = 0,p = 1;
    char ch = getchar();
    while(ch < '0' || ch > '9')
    {
        if(ch == '-')
            p = -1;
        ch = getchar();
    }
    while(ch >= '0' && ch <= '9')
    {
        (sum *= 10) += ch - '0';
        ch = getchar();
    }
    return sum * p;
}
const int maxn = 100005;
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 = 0;
    for(int i = 1;i <= n;i++)
        if(p[i].x > 0 && p[i].y > 0)
        {
            if(p[i].y > f[len])
                f[++len] = p[i].y;
            else
            if(p[i].y< f[1])
                f[1] = p[i].y;
            else
                f[lower_bound(f + 1,f + len + 1,p[i].y) - f] = p[i].y;
        }
        return len;
}
int main()
{
    n = read();
    a = read(),b = read(),c = read(),d = read();
    for(int i = 1;i <= n;i++)
    {
        int x = read(),y = read();
        p[i].x = c * x - d * y;
        p[i].y = b * y - a * x;
    }
    sort(p+1,p + n + 1,cmp);
    printf("%lld",lis());
    return 0;
}