Submission #1056392

#TimeUsernameProblemLanguageResultExecution timeMemory
1056392ReLiceAliens (IOI16_aliens)C++17
41 / 100
121 ms261632 KiB
#include "aliens.h"
#include <bits/stdc++.h>
#define ll long long
#define sz size()
#define all(x) x.begin(),x.end()
#define vll vector<ll>
#define str string
#define pb push_back
#define pof pop_front()
#define pf push_front
#define pob pop_back()
#define bc back()
using namespace std;
const ll N=4e3+5;
struct Line{
	ll m,b;
	
	ll operator () (ll x){return m * x + b;}
	
	bool ok(Line x, Line y){
		ll t1 = (x.b - b);
		ll b1 = (m - x.m);
		ll t2 = (y.b - b);
		ll b2 = (m - y.m);
		
		return t1 * b2 >= t2 * b1;
	}
	
};

ll sq(ll x){
	return x*x;
}
long long dp[N][N];
long long take_photos(int N, int M, int K, vector<int> R, vector<int> C) {
	ll i,q;
	ll n=N,m=M,k=K;
	vll len, nxt;
	vll c, r;
	for(auto i : C)c.pb(i);
	for(auto i : R)r.pb(i);
	
	
	{//deleting unnecessary ones
		vll mx(m, m), nr;
		
		for(i=0;i<n;i++){
			if(r[i] < c[i]) swap(r[i], c[i]);
			
			mx[r[i]] = min(mx[r[i]], c[i]);
		} 
		for(i=m-1;i>=0;i--){
			
			if(mx[i] > i)continue;
			
			if(nr.empty() || mx[nr.bc] > mx[i]){
				nr.pb(i);
				len.pb(i-mx[i]+1);
			}
		}
		
		nr.pb(-1), len.pb(-1);//changing indexation

		reverse(all(nr));
		reverse(all(len));
		
		r=nr;
		n=r.size()-1;
		k = min(k, n);
	}
	
	c.clear();
	c.pb(0);
	nxt.clear();
	//~ cout<<endl;
	for(i=1;i<=n;i++){
		nxt.pb(r[i] - len[i]);
		c.pb(nxt.bc + 1);
		
		len[i - 1] = r[i - 1] - nxt[i - 1] ;
		len[i - 1] = max(len[i - 1], 0ll);
		
		//~ cout<<r[i - 1]<<' '<<nxt[i - 1]<<endl;
		//~ cout<<len[i - 1]<<endl;
	}
	//~ cout<<endl;
	len[0]=0;
	nxt.pb(r[n]);
	
	memset(dp, 0x3f, sizeof(dp));
	dp[0][1]=0;
	
	vector<deque<Line>> ch(k+5);
	
	//~ for(i=0;i<=k;i++)ch[i].pb({-2 * nxt[0], nxt[0] * nxt[0]});
	
	for(i=1;i<=n;i++){ 
		for(q=1;q<=k;q++){
			auto &dq = ch[q-1];
			
			ll x = r[i];
			while(dq.sz > 1 && dq[0](x) > dq[1](x)){
				dq.pof;
			}
			
			if(dq.sz){
				dp[i][q] = sq(r[i]) + dq[0](x);	
			}
			else dp[i][q] = sq(r[i] - nxt[0]);
			
		}
		
		for(q=1;q<=k;q++){
			ll m = (-2) * nxt[i];
			ll b = nxt[i] * nxt[i] - len[i] * len[i] + dp[i][q];
			Line cur = {m, b};
			
			//~ if(q == 1){
				//~ cout<<i<<endl;
				//~ cout<<m<<' '<<b<<endl;
				//~ cout<<endl;
			//~ }
			
			auto &dq = ch[q];
			while((ll) dq.sz > 1 && dq[dq.sz - 2].ok(dq.bc, cur)) dq.pob;
			dq.pb(cur); 
		}
	}
	
	long long ans=dp[n+1][0];
	for(i=0;i<=k;i++) ans=min(ans,dp[n][i]);
    
    return ans;
}





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