Submission #62366

#	Time	Username	Problem	Language	Result	Execution time	Memory
62366		fallingstar	Shortcut (IOI16_shortcut)	C++14	38 / 100	2052 ms	1816 KiB

shortcut

#include "shortcut.h"
#include <iostream>
#include <algorithm>

#define long long long

using namespace std;

const int N = 1e6 + 2;
const int LN = 20;
const long INF = 1LL << 60;

int n, sec[N];
long dmain[N], express;
int rmqp[LN][N], rmqs[LN][N];

void BuildRMQ()
{
    for (int i = 0; i < n; ++i)
        rmqp[0][i] = rmqs[0][i] = i;

    for (int j = 1; j < LN; ++j)
        for (int i = 0; i + (1 << j) <= n; ++i)
        {
            rmqp[j][i] = max(rmqp[j - 1][i], rmqp[j - 1][i + (1 << (j - 1))], [](int x, int y) {
                return dmain[x] + sec[x] < dmain[y] + sec[y];
            });
            rmqs[j][i] = max(rmqs[j - 1][i], rmqs[j - 1][i + (1 << (j - 1))], [](int x, int y) {
                return -dmain[x] + sec[x] < -dmain[y] + sec[y];
            });
        }
}

int QueryPref(int l, int r)
{
    int k = 31 - __builtin_clz(r - l + 1);
    return max(rmqp[k][l], rmqp[k][r - (1 << k) + 1], [](int x, int y) {
                return dmain[x] + sec[x] < dmain[y] + sec[y];
            });
}
int QuerySuff(int l, int r)
{
    int k = 31 - __builtin_clz(r - l + 1);
    return max(rmqs[k][l], rmqs[k][r - (1 << k) + 1], [](int x, int y) {
                return -dmain[x] + sec[x] < -dmain[y] + sec[y];
            });
}
inline long GetPref(int l, int r)
{
    if (l > r) return -INF;
    int u = QueryPref(l, r);
    return dmain[u] + sec[u];
}
inline long GetSuff(int l, int r)
{
    if (l > r) return -INF;
    int u = QuerySuff(l, r);
    return dmain[n - 1] - dmain[u] + sec[u];
}

void Prep()
{
    BuildRMQ();
}

void Maximize(long &a, long b) { a = max(a, b); }
inline long Dist(int u, int v) { return abs(dmain[v] - dmain[u]); }

long GetAns(int u, int v)
{
    if (u > v) swap(u, v);

    bool right = false;

    long ans = 0;
    for (int i = 0, midR = u; i < n; ++i)
    {
        long distR = 0;

        if (i < v)
        {
            while (midR < v && Dist(i, midR + 1) < Dist(midR + 1, v) + express + Dist(u, i)) ++midR;
            Maximize(distR, GetPref(v, n - 1) - dmain[v] + min(express + Dist(u, i), Dist(v, i)));
            Maximize(distR, GetSuff(midR + 1, v) - Dist(n - 1, v) + express + Dist(u, i));
            Maximize(distR, GetPref(i + 1, midR) - dmain[i]);
        }
        else
            Maximize(distR, GetPref(i + 1, n - 1) - dmain[i]);

        ans = max(ans, sec[i] + distR);
    }
    return ans;
}

long find_shortcut(int n_, vector<int> a_, vector<int> d_, int c_)
{
    n = n_, express = c_;
    for (int i = 1; i < n; ++i)
        dmain[i] = dmain[i - 1] + a_[i - 1];
    copy(d_.begin(), d_.end(), sec);
    Prep();

    long cur = 0, res = GetAns(0, 1);
//    for (int l = 0, r = 0; l + 1 < n; ++l)
//    {
//        int lo = l + 1, hi = n - 1;
//        while (lo + 1 < hi)
//        {
//            int ml = (lo + lo + hi) / 3, mr = (lo + hi + hi) / 3;
//            if (Dist(l, ml) <= express) lo = ml + 1;
//            else
//                if (GetAns(l, ml) <= GetAns(l, mr)) hi = mr - 1;
//                else lo = ml + 1;
//        }
//        for (int i = lo; i <= hi; ++i) res = min(res, GetAns(l, i));
////        cout << "#" << l << ' ' << lo << ' ' << hi << ' ' << '\n';
//    }
    for (int i = 0; i < n; ++i)
        for (int j = i + 1; j < n; ++j)
        {
            long val = GetAns(i, j);
            if (Dist(i, j) <= express) continue;
//            cout << i << ' ' << j << ' ' << val << '\n';
            res = min(res, val);
        }
    return res;
}

Compilation message (stderr)

shortcut.cpp: In function 'long long int GetAns(int, int)':
shortcut.cpp:73:10: warning: unused variable 'right' [-Wunused-variable]
     bool right = false;
          ^~~~~
shortcut.cpp: In function 'long long int find_shortcut(int, std::vector<int>, std::vector<int>, int)':
shortcut.cpp:103:10: warning: unused variable 'cur' [-Wunused-variable]
     long cur = 0, res = GetAns(0, 1);
          ^~~

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