Submission #278955

#	Time	Username	Problem	Language	Result	Execution time	Memory
278955		tinjyu	Aliens (IOI16_aliens)	C++14	0 / 100	1 ms	384 KiB

aliens

#include "aliens.h"
#include <iostream>
#include <algorithm>
using namespace std;
struct node{
	long long int x,y;
}a[1000005];
long long int dp[400005],x[1000005],y[1000005],t[1000005][3],g[100005];
bool cmp(node a,node b)
{
	if(a.x<b.x)return 1;
	if(a.x>b.x)return 0;
	if(a.y<a.y)return 1;
	return 0;
}
double check(long long int a,long long int b)
{
	return (t[a][0]-t[b][0])/(t[a][1]-t[b][1]);
}
long long take_photos(int n, int m, int k, std::vector<int> r, std::vector<int> c) {
    for(int i=0;i<n;i++)
    {
    	a[i].x=r[i];
    	a[i].y=c[i];
    	if(a[i].y<a[i].x)
    	{
    		swap(a[i].x,a[i].y);
		}
	}
	sort(a,a+n,cmp);
	long long int cnt=1;
	x[1]=a[0].x;
	y[1]=a[0].y;
	for(int i=1;i<n;i++)
	{
		if(a[i].x>x[cnt] && a[i].y>=y[cnt])
		{
			cnt++;
			x[cnt]=a[i].x;
			y[cnt]=a[i].y;
		}
		else if(a[i].x==x[cnt] && a[i].y>y[cnt])
		{
			x[cnt]=a[i].x;
			y[cnt]=a[i].y;
		}
	}
	n=cnt;
	x[0]=-1;
	y[0]=-1;
	long long int le=0,ri=m,ans;
	while(le<=ri)
	{
		long long int mid=(le+ri)/2;
		int st=1,en=0;
		//cout<<mid<<endl;
		dp[1]=0;
		t[1][2]=0;
		for(int i=1;i<=n;i++)
		{
			while(en>=st+3 && check(st,st+1)<2*y[i])st++;
			int p=t[st][2];
			if(y[p-1]-x[p]+1>0 && p!=0)dp[i]=mid+dp[p]+(y[i]-x[p+1]+1)*(y[i]-x[p+1]+1)-(y[p-1]-x[p]+1)*(y[p-1]-x[p]+1);
			else dp[i]=mid+dp[p]+(y[i]-x[p+1]+1)*(y[i]-x[p+1]+1);
			g[i]=g[p]+1;
			en++;
			t[en][0]=dp[i]+x[i+1]*x[i+1]-2*x[i+1];
			t[en][1]=x[i+1];
			t[en][2]=i;
			while(en>=st+2 && check(en,en-2)<check(en-1,en-2))en--;
			//cout<<dp[i]<<" ";
		}
		//cout<<endl;
		if(g[n]<=k)
		{
			ans=dp[n]-mid*g[n];
			ri=mid-1;
		}
		else le=mid+1;
	}
	return ans;
}

Compilation message (stderr)

aliens.cpp: In function 'bool cmp(node, node)':
aliens.cpp:13:8: warning: self-comparison always evaluates to false [-Wtautological-compare]
   13 |  if(a.y<a.y)return 1;
      |     ~~~^~~~
aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:81:9: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   81 |  return ans;
      |         ^~~

• Subtask 1: 0 / 4
• Subtask 2: 0 / 12
• Subtask 3: 0 / 9
• Subtask 4: 0 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 40