Submission #292600

#	Time	Username	Problem	Language	Result	Execution time	Memory
292600		amoo_safar	Shortcut (IOI16_shortcut)	C++17	0 / 100	8 ms	512 KiB

shortcut

#include "shortcut.h"

#include <bits/stdc++.h>

#pragma GCC optimize("Ofast")

#define F first
#define S second

using namespace std;

typedef long long ll;

typedef pair<ll, ll> pll;

const int N = 3010;
const ll Inf = 1e18;

ll ps[N];
ll maxp[N][N], maxn[N][N];
ll pre[N], suf[N];
ll d[N];
ll n, c;


pll Solve(ll i, ll j){

	ll Di, Dj, dia, dia2;
	ll cyc;

	Di = ps[i] + maxn[0][i];
	Dj = maxp[j][n - 1] - ps[j];
	cyc = c + ps[j] - ps[i];

	ll C2 = cyc / 2;

	dia2 = Di + Dj + min(c, cyc - c);
	dia = 0;
	for(int k = i + 1; k < j; k++){
		//ll po = lower_bound(ps, ps + n, ps[k]);

		//for(int k2 = k + 1; k2 < j; k2++){
		//	dia = max(dia, d[k] + d[k2] + min(ps[k2] - ps[k], cyc - (ps[k2] - ps[k]) ) );
		//}
		
		dia = max(dia, Di + d[k] + min(ps[k] - ps[i], cyc - (ps[k] - ps[i])));
		dia2 = max(dia2, Dj + d[k] + min(ps[j] - ps[k], cyc - (ps[j] - ps[k])));
	}

	int po = i + 1;
	for(int k = i + 1; k < j; k++){
		while((po < j - 1) && (ps[po + 1] - ps[k] <= C2)) po ++;
		dia = max(dia, d[k] + maxp[k][po] - ps[k]);
		if(po < j - 1){
			dia = max(dia, d[k] + (cyc + maxn[po + 1][j - 1] + ps[k] ));
		}
	}
	po = j - 1;
	for(int k = j - 1; k > i; k--){
		while((po > i + 1) && (ps[k] - ps[po - 1] <= C2)) po --;
		dia = max(dia, d[k] + maxn[po][k] + ps[k]);
		if(po > i + 1){
			dia = max(dia, d[k] + (cyc + maxp[i + 1][po - 1] - ps[k] ));
		}
	}

	dia2 = max(dia2, suf[j]);
	dia = max(dia, pre[i]);
	//cerr << "^ " << dia << ' ' << dia2 << '\n';
	return make_pair(dia, dia2);
}

long long find_shortcut(int _n, vector<int> _l, vector<int> _d, int _c){
	n = _n; c = _c;
	for(int i = 0; i < n; i++) d[i] = _d[i];
	ps[0] = 0;
	for(int i = 1; i < n; i++) ps[i] = ps[i - 1] + _l[i - 1];

	// Calc Maxp
	for(int i = 0; i < n; i++) maxp[i][i] = d[i] + ps[i];
	for(int i = 0; i < n; i++) maxn[i][i] = d[i] - ps[i];
	for(int ln = 2; ln <= n; ln++){
		for(int i = 0; i + ln <= n; i++){
			int j = i + ln - 1;
			maxp[i][j] = max(maxp[i + 1][j], maxp[i][j - 1]);
			maxn[i][j] = max(maxn[i + 1][j], maxn[i][j - 1]);
		}
	}
	// Calc pre
	pre[0] = d[0];
	for(int i = 1; i < n; i++){
		pre[i] = max(pre[i - 1], d[i] + ps[i] + maxn[0][i - 1]);
	}	
	suf[n - 1] = d[n - 1];
	for(int i = n - 2; i >= 0; i--){
		suf[i] = max(suf[i + 1], d[i] - ps[i] + maxp[i + 1][n - 1]);
	}
	// Calc dia
	ll X = 0, Y = 0, D = -1;
	for(int i = 0; i < n; i++){	
		for(int j = i + 1; j < n; j++){
			if(D < ps[j] - ps[i] + d[i] + d[j]){
				D = ps[j] - ps[i] + d[i] + d[j];
				X = i; Y = j;
			}
			if(D == ps[j] - ps[i] + d[i] + d[j] && Y - X > j - i){
				X = i;
				Y = j;
			}
		}
	}
	ll dia, dia2, ans = Inf;
	pll res;
	//vector<pll> V;
	vector<ll> V2;
	vector<ll> opt;
	for(int i = X; i + 1 <= Y; i++){
		pll resL = {Inf, Inf}, resR = {Inf, Inf};
		int L = i, R = Y + 1, mid;
		while(L + 1 < R){
			mid = (L + R) >> 1;
			res = Solve(i, mid);
			if(res.F <= res.S){
				L = mid;
				resL = res;
			} else{
				R = mid;
				resR = res;
			}
		}
		pll best = {Inf, Inf};
		dia = Inf;
		opt.push_back(L);
		/*
		if(L != i){
			res = resL;
			if(max(best.F, best.S) > max(res.F, res.S))
				best = res;
		}

		if(R != n){
			res = resR;
			if(max(best.F, best.S) > max(res.F, res.S))
				best = res;
		}
		*/
		dia = min(max(resL.F, resL.S), max(resR.F, resR.S));
		ans = min(ans, dia);
		V2.push_back(dia);
		//cerr << "# " << ans << '\n';
		/*
		assert(best != pll(Inf, Inf));
		ans = min(ans, max(best.F, best.S));
		V2.push_back(max(best.F, best.S));
		*/
		//V.push_back(best);
		/*
		V.clear();
		for(int j = i + 1; j < n; j++){
			res = Solve(i, j);
			dia = max({res.first, res.second});
			ans = min(ans, dia);
			V.push_back(res);
		}
		int sz = (int) V.size();
		for(int j = 0; j + 1 < sz; j++){
			assert(V[j].first <= V[j + 1].first);
			assert(V[j].second >= V[j + 1].second);	
		}
		*/
	}
	
	int sz = (int) opt.size();
	bool flg = false;
	for(int j = 1; j < sz; j++){
		assert(opt[j - 1] <= opt[j]);
		/*
		if(V2[j] == V2[j + 1]) continue;
		if(V2[j] < V2[j + 1]) flg = true;
		if(V2[j] > V2[j + 1] && flg) //continue;
			assert(0);
		*/
	}

	return ans;
}

Compilation message (stderr)

shortcut.cpp: In function 'long long int find_shortcut(int, std::vector<int>, std::vector<int>, int)':
shortcut.cpp:131:7: warning: variable 'best' set but not used [-Wunused-but-set-variable]
  131 |   pll best = {Inf, Inf};
      |       ^~~~
shortcut.cpp:112:10: warning: unused variable 'dia2' [-Wunused-variable]
  112 |  ll dia, dia2, ans = Inf;
      |          ^~~~
shortcut.cpp:174:7: warning: unused variable 'flg' [-Wunused-variable]
  174 |  bool flg = false;
      |       ^~~

• 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