Submission #1031661

#	Time	Username	Problem	Language	Result	Execution time	Memory
1031661		pcc	Shortcut (IOI16_shortcut)	C++17	0 / 100	41 ms	72324 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>
using namespace std;

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC taget("avx2,popcnt,sse4")

#define pll pair<ll,ll>
#define fs first
#define sc second
#define pii pair<int,int>
#define ll long long

#define DEBUG(T) cerr<<#T<<":"<<T<<endl;

const ll inf = 1e18;
const int mxn = 3030;
ll pref[mxn];
ll arr[mxn];
int C,N;
ll dp[mxn][mxn];
ll P[mxn],S[mxn];
ll pans[mxn],sans[mxn];

ll brr[mxn];

ll chain(ll R,int s,int e){
	return pref[e]-pref[s]+brr[e]+brr[s];
}
ll cycle(ll R,int s,int e){
	return R+C-(pref[e]-pref[s])+brr[s]+brr[e];
}

ll calc(int a,int b){
	if(dp[a][b] != -1)return dp[a][b];
	if(a == b)return dp[a][b] = pans[N-1];
	for(int i = a;i<=b;i++)brr[i] = arr[i];
	brr[a] = P[a],brr[b] = S[b];
	ll ans = *max_element(brr+a,brr+b+1);
	ans = max({ans,pans[a],sans[b]});
	ll cyc = -inf;
	ll R = pref[b]-pref[a];
	ll re = 0;
	int ptr = a;
	multiset<ll> st;
	st.insert(-inf);
	for(int i = a;i<=b;i++){
		while(ptr<i&&cycle(R,ptr,i)<chain(R,ptr,i)){
			st.erase(st.find(brr[ptr]-pref[ptr]));
			cyc = max(cyc,brr[ptr]+pref[ptr]);
			ptr++;
		}
		ll chn = *st.rbegin();
		ans = max({ans,pref[i]+brr[i]+chn,cyc+brr[i]-pref[i]+R+C});
		st.insert(brr[i]-pref[i]);
	}
	return dp[a][b] = ans;
}

void init(){
	ll pp = -inf;
	for(int i = 0;i<N;i++){
		pans[i] = arr[i];
		if(i)pans[i] = max(pans[i],pans[i-1]);
		pans[i] = max(pans[i],arr[i]+pref[i]+pp);
		pp = max(pp,-pref[i]+arr[i]);
	}
	pp = -inf;
	for(int i = N-1;i>=0;i--){
		sans[i] = arr[i];
		if(i != N-1)sans[i] = max(sans[i],sans[i+1]);
		sans[i] = max(sans[i],arr[i]-pref[i]+pp);
		pp = max(pp,pref[i]+arr[i]);
	}
	P[0] = arr[0];S[N-1] = arr[N-1];
	for(int i = 1;i<N;i++)P[i] = max(P[i-1]+pref[i]-pref[i-1],arr[i]);
	for(int i = N-2;i>=0;i--)S[i] = max(S[i+1]+pref[i+1]-pref[i],arr[i]);
}


ll ans[mxn];

void dc(int tl,int tr,int l,int r){
	int mid = (l+r)>>1;
	assert(tl<=mid);
	int good = tl;
	for(int i = tl;i<=min(mid,tr);i++){
		if(calc(good,mid)>=calc(i,mid))good = i;
	}
	ans[mid] = min(ans[mid],calc(good,mid));
	cerr<<"DC: "<<tl<<' '<<tr<<' '<<l<<' '<<r<<' '<<mid<<":"<<good<<','<<calc(good,mid)<<endl;
	if(l != mid)dc(good,tr,l,mid-1);
	if(mid != r)dc(tl,good,mid+1,r);
	return;
}

void f(int l,int r){
	if(l == r){
		ans[l] = min(ans[l],pans[N-1]);
		return;
	}
	int mid = (l+r)>>1;
	dc(l,mid,mid+1,r);
	return;
}

long long find_shortcut(int n, std::vector<int> l, std::vector<int> d, int c){
	memset(dp,-1,sizeof(dp));
	N = n,C = c;
	for(int i = 0;i<N;i++)arr[i] = d[i];
	for(int i = 0;i+1<N;i++){
		pref[i+1] = pref[i]+l[i];
	}
	init();
	fill(ans,ans+N,inf);

	f(0,N-1);
	return *min_element(ans,ans+N);
}

Compilation message (stderr)

shortcut.cpp:6: warning: ignoring '#pragma GCC taget' [-Wunknown-pragmas]
    6 | #pragma GCC taget("avx2,popcnt,sse4")
      | 
shortcut.cpp: In function 'long long int calc(int, int)':
shortcut.cpp:43:5: warning: unused variable 're' [-Wunused-variable]
   43 |  ll re = 0;
      |     ^~

• 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