Submission #1266129

#	Time	Username	Problem	Language	Result	Execution time	Memory
1266129		gustavo_d	Shortcut (IOI16_shortcut)	C++20	0 / 100	0 ms	328 KiB

shortcut

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

typedef long long ll;

const int MAXN = 3000;
const ll INF = 1e18;

int n;
ll pf[MAXN], sf[MAXN]; int p[MAXN], pfPai[MAXN], sfPai[MAXN];
ll pos[MAXN+2];

ll find_shortcut(int N, vector<int> l, vector<int> d, int c) {
    n = N;
    pf[0] = d[0]; pfPai[0] = 0;
    for (int i=0; i<n-1; i++) {
        pfPai[i+1] = (d[i+1] >= pf[i]+l[i] ? i+1 : pfPai[i]);
        pf[i+1] = max(
            (ll)d[i+1],
            pf[i] + l[i]
        );
    }
    sf[n-1] = d[n-1]; sfPai[n-1] = n-1;
    for (int i=n-2; i>=0; i--) {
        sfPai[i] = (d[i] >= sf[i+1] + l[i] ? i : sfPai[i+1]);
        sf[i] = max(
            (ll)d[i],
            sf[i+1] + l[i]
        );
    }

    int center = 0;
    for (int i=0; i<n-1; i++) {
        if (pf[i] + sf[i+1] + l[i] > pf[center] + sf[center+1] + l[center])
            center = i;
    }

    n = 0; pos[n++] = 0;
    bool left = false, right = false;
    if (d[pfPai[center]] > 0) {
        left = true;
        p[n] = pfPai[center];
        pos[n++] = d[pfPai[center]];
    }
    for (int i=pfPai[center]; i<sfPai[center+1]; i++) {
        pos[n] = pos[n-1] + l[i];
        p[n] = i+1;
        n++;
    }
    if (d[sfPai[center+1]] > 0) {
        right = true;
        pos[n] = pos[n-1] + d[sfPai[center+1]];
        n++;
    }

    // for (int i=0; i<n; i++) {
    //     cout << pos[i] << ' ';
    // }
    // cout << endl;
    ll ans = pf[center] + sf[center + 1] + l[center];
    for (int i=left; i<n-right; i++) {
        for (int j=i+1; j<n-right; j++) {
            // cout << i << ' ' << j << ' ' << pos[j] - pos[i] << endl;
            if (pos[j] - pos[i] <= c) continue;
            ll res = max({
                pos[i] + c + pos[n-1] - pos[j],
                (p[i] > 0 ? pf[p[i]-1] + l[p[i]-1] + d[p[i]] : 0LL),
                (p[j] < N-1 ? sf[p[j]+1] + l[p[j]] + d[p[j]] : 0LL)
            });
            // cout << pos[i] << ' ' << c << ' ' << pos[n-1] << ' ' << pos[j] << endl;
            for (int k=i+1; k<j; k++) {
                // cout << max(min(pos[k], pos[j]-pos[k]+c+pos[i]),
                //     min(pos[n-1]-pos[k], pos[k]-pos[i]+c+pos[n-1]-pos[j])) + d[p[k]] << ' ';
                res = max({
                    res,
                    min(pos[k], pos[j]-pos[k]+c+pos[i]) + d[p[k]],
                    min(pos[n-1]-pos[k], pos[k]-pos[i]+c+pos[n-1]-pos[j]) + d[p[k]]
                });
            }
            // cout << endl;
            // cout << i << ' ' << j << ' ' << res << endl;
            ans = min(ans, res);
        }
    }
    return ans;
}

Compilation message (stderr)

shortcut.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~
shortcut_c.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~

• 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