Submission #165597

#	Time	Username	Problem	Language	Result	Execution time	Memory
165597		Segtree	Shortcut (IOI16_shortcut)	C++14	0 / 100	2 ms	376 KiB

shortcut

#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include"shortcut.h"
using namespace std;
typedef long long ll;
#define chmin(a,b) a=min(a,b)
#define chmax(a,b) a=max(a,b)
#define N 510
ll r[N],d[N],n,cost;
ll solve(ll p,ll q){
    if(p>=q)return 1e17;
    if(r[q]-r[p]<=cost)return 1e17;
    ll x=-1e17;
    for(int i=0;i<=p;i++){
	chmax(x,r[p]-r[i]+d[i]);
    }
    ll y=-1e17;
    for(int i=q;i<n;i++){
	chmax(y,r[i]-r[q]+d[i]);
    }
    ll ans=x+y+cost;
    for(int i=p+1;i<=q-1;i++){
	chmax(ans,x+d[i]+min(r[i]-r[p],r[q]-r[i]+cost));
	chmax(ans,y+d[i]+min(r[i]-r[p]+cost,r[q]-r[i]));
    }
    
    ll mik=1e17;
    for(int i=0;i<=p;i++){
	chmax(ans,r[i]+d[i]-mik);
	chmin(mik,r[i]-d[i]);
    }
    mik=1e17;
    for(int i=q;i<n;i++){
	chmax(ans,r[i]+d[i]-mik);
	chmin(mik,r[i]-d[i]);
    }
    
    if(p<q-1){
	ll key=cost+r[q]-r[p];
	vector<ll> rs,ds;
	for(int k=0;k<=2;k++){
	    for(int i=p;i<=q;i++){
		rs.push_back(r[i]-r[p]+k*key);
		ds.push_back(d[i]);
	    }
	}
	int j=1;
	deque<pair<ll,ll> > Q;
	for(int i=0;i<=q-p;i++){
	    for(;j<rs.size()&&(rs[j]-rs[i])*2LL<=key;j++){
		while(!Q.empty()&&Q.back().first<=rs[j]+ds[j])Q.pop_back();
		Q.push_back(make_pair(rs[j]+ds[j],j)); 
	    }
	    while(!Q.empty()&&Q.front().second<=i)Q.pop_front();
	    if(!Q.empty())chmax(ans,Q.front().first-rs[i]+ds[i]);
	}
    }
    return ans;
}
ll dfs(ll l,ll r,ll lo,ll up){
    if(l>r)return 1e17;
    ll m=(l+r)>>1;
    ll mi=1e17,pnt=-1;
    for(int i=lo;i<=up;i++){
	ll res=solve(m,i);
	if(mi>res){
	    mi=res;
	    pnt=i;
	}
    }
    if(l==r)return mi;
    chmin(mi,dfs(l,m-1,lo,pnt));
    chmin(mi,dfs(m+1,r,pnt,up));
    return mi;
}
ll find_shortcut(int nn,vector<int> l,vector<int> dd,int cc){
    n=nn,cost=cc;
    for(int i=0;i<n;i++)d[i]=dd[i];
    r[0]=0;
    for(int i=0;i<n-1;i++)r[i+1]=r[i]+l[i];
    ll ans=-1e17;
    for(int i=0;i<n;i++)for(int j=i+1;j<n;j++){
	chmax(ans,r[j]-r[i]+d[i]+d[j]);
    }
    ll bef=-1;
    for(int p=0;p<n-1;p++){
	ll mi=1e17,pnt=-1;
	for(int q=p+1;q<n;q++){
	    ll res=solve(p,q);
	    chmin(ans,res);
	    if(mi>res){
		mi=res;
		pnt=q;
	    }
	}
	if(bef>pnt)return -1;
	bef=pnt;
    }
    //chmin(ans,dfs(0,n-1,0,n-1));
    return ans;
}

Compilation message (stderr)

shortcut.cpp: In function 'll solve(ll, ll)':
shortcut.cpp:52:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for(;j<rs.size()&&(rs[j]-rs[i])*2LL<=key;j++){
           ~^~~~~~~~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 14
• Subtask 3: 0 / 8
• Subtask 4: 0 / 7
• Subtask 5: 0 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3