Submission #777874

#	Time	Username	Problem	Language	Result	Execution time	Memory
777874		zsombor	Dreaming (IOI13_dreaming)	C++17	18 / 100	38 ms	13728 KiB

dreaming

#include <iostream>
#include <algorithm>
#include <vector>
#include "dreaming.h"
using namespace std;

int mn = 1e9, ans = 0;
vector <vector <pair <int, int>>> g(1e5);
vector <int> par(1e5, -1);
vector <int> down1(1e5, 0);
vector <int> down2(1e5, 0);
vector <int> up(1e5, 0);
vector <int> far(1e5, 0);
vector <bool> done(1e5, false);
vector <int> MN;

void dfs1(int x) {
    for (auto p : g[x]) {
        int i = p.first, w = p.second;
        if (i == par[x]) continue;
        par[i] = x;
        dfs1(i);
        if (down1[i] + w > down1[x]) down1[x] = down1[i] + w;
        else if (down1[i] + w > down2[x]) down2[x] = down1[i] + w;
    }
}

void dfs2(int x) {
    for (auto p : g[x]) {
        int i = p.first, w = p.second;
        if (i == par[x]) continue;
        up[i] = max(up[x], (down1[x] == down1[i] + w ? down2[x] : down1[x])) + w;
        dfs2(i);
    }
}

void dfs3(int x) {
    far[x] = max(down1[x], up[x]);
    mn = min(mn, far[x]);
    ans = max(ans, far[x]);
    done[x] = true;
    for (auto p : g[x]) {
        int i = p.first;
        if (i == par[x]) continue;
        dfs3(i);
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    for (int i = 0; i < M; i++) {
        g[A[i]].push_back({ B[i],T[i] });
        g[B[i]].push_back({ A[i],T[i] });
    }
    for (int i = 0; i < N; i++) {
        if (done[i]) continue;
        dfs1(i);
        dfs2(i);
        dfs3(i);
        MN.push_back(mn);
        mn = 1e9;
    }
    sort(MN.begin(), MN.end());
    reverse(MN.begin(), MN.end());
    if (MN.size() >= 2) ans = max(ans, MN[0] + MN[1] + L);
    if (MN.size() >= 3) ans = max(ans, MN[1] + MN[2] + 2 * L);
    return ans;
}

• Subtask 1: 0 / 14
• Subtask 2: 0 / 10
• Subtask 3: 0 / 23
• Subtask 4: 18 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23