Submission #1022518

#	Time	Username	Problem	Language	Result	Execution time	Memory
1022518		RaresFelix	Shortcut (IOI16_shortcut)	C++17	38 / 100	2065 ms	282932 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;

const ll INF = 1e18;

bool posib(int n, vll alpha, vll beta, vll s, ll l, ll c) {
    vll gamma(n, 0);
    for(int i = 0; i < n; ++i)
        gamma[i] = l - alpha[i];
    vector<vll> DP1(n, vll(n, -INF));
    vector<vll> DP2(n, vll(n, -INF));
    vector<vll> DP3(n, vll(n, -INF));
    vector<vll> DP4(n, vll(n, -INF));
    for(int i = 0; i < n; ++i)
        for(int j = i + 1; j < n; ++j) {
            if(beta[j] > gamma[i]) {
                DP1[i][j] = alpha[i] + alpha[j];
                DP2[i][j] = beta[j] + alpha[i];
                DP3[i][j] = beta[i] + alpha[j];
                DP4[i][j] = beta[i] + beta[j];
            }
        }
    auto propag = [&](int i, int len) {
        int j = i + len;
        if(j >= n) return;
        if(j) {
            DP1[i][j] = max(DP1[i][j], DP1[i][j - 1]);
            DP3[i][j] = max(DP3[i][j], DP3[i][j - 1]);
        }
        if(i) {
            DP1[i][j] = max(DP1[i][j], DP1[i - 1][j]);
            DP2[i][j] = max(DP2[i][j], DP2[i - 1][j]);
        }
        if(i + 1 < n) {
            DP3[i][j] = max(DP3[i + 1][j], DP3[i][j]);
            DP4[i][j] = max(DP4[i + 1][j], DP4[i][j]);
        }
        if(j + 1 < n) {
            DP2[i][j] = max(DP2[i][j], DP2[i][j + 1]);
            DP4[i][j] = max(DP4[i][j], DP4[i][j + 1]);
        }
    };
    for(int i = 0; i < n; ++i) 
        for(int j = 0; j < n; ++j)
            propag(i, j);
    for(int i = 0; i < n; ++i) 
        for(int j = n - 1; j >= 0; --j)
            propag(i, j);
    for(int i = n - 1; i >= 0; --i)
        for(int j = 0; j < n; ++j)
            propag(i, j);
    for(int i = n - 1; i >= 0; --i)
        for(int j = n - 1; j >= 0; --j)
            propag(i, j);
    for(int a = 0; a < n; ++a)
        for(int b = a; b < n; ++b) {
            bool ok = true;
            ok &= DP1[a][b] + s[a] + s[b] + c <= l;
            ok &= DP2[a][b] + s[a] - s[b] + c <= l;
            ok &= DP3[a][b] - s[a] + s[b] + c <= l;
            ok &= DP4[a][b] - s[a] - s[b] + c <= l;
            if(ok) return true;
        }
    return false;
}

ll find_shortcut(int n, vi l, vi d, int c) {
    vll s(n, 0), alpha(n, 0), beta(n, 0);

    for(int i = 1; i < n; ++i) {
        s[i] = s[i - 1] + l[i - 1];
    }
    for(int i = 0; i < n; ++i) {
        alpha[i] = d[i] - s[i];
        beta[i] = d[i] + s[i];
    }
    ll st = 0, dr = INF, mij;
    while(st < dr) {
        mij = (st + dr) / 2;
        if(posib(n, alpha, beta, s, mij, c))
            dr = mij;
        else st = mij + 1;
    }

    return st;
}

• 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