Submission #574676

#	Time	Username	Problem	Language	Result	Execution time	Memory
574676		talant117408	Dreaming (IOI13_dreaming)	C++17	18 / 100	57 ms	16336 KiB

dreaming

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

//~ #ifndef EVAL
//~ #include "grader.cpp"
//~ #endif
 
using namespace std;
 
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
 
#define pb                  push_back
#define mp                  make_pair
#define lb                  lower_bound
#define ub                  upper_bound
#define all(v)              (v).begin(),(v).end()
#define sz(v)               int((v).size())
#define do_not_disturb      ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl                '\n'

const int N = 1e5+7;
int used[N];
int n, l, compN, comp[N], furthest[N];
pii compLowest[N], compEnds[N];
vector <pii> graph[N];

void dfs(int v, int p) {
    used[v] = 1;
    comp[v] = compN;
    for (auto to : graph[v]) {
        if (to.first == p) continue;
        dfs(to.first, v);
    }
}

int df, vf;
int distFrom[N][2];

void get_furthest(int v, int p, int dist = 0) {
    if (dist > df) {
        df = dist;
        vf = v;
    }
    for (auto to : graph[v]) {
        if (to.first == p) continue;
        get_furthest(to.first, v, dist+to.second);
    }
}

void calc_dist(int v, int p, int origin, int flag, int d = 0) {
    if (flag == 0) {
        distFrom[v][0] = d;
    }
    else {
        distFrom[v][1] = d;
    }
    for (auto to : graph[v]) {
        if (to.first == p) continue;
        calc_dist(to.first, v, origin, flag, d+to.second);
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    n = N;
    for (int i = 0; i < M; i++) {
        graph[A[i]].pb(mp(B[i], T[i]));
        graph[B[i]].pb(mp(A[i], T[i]));
    }
    for (int i = 1; i <= n; i++) {
        if (!used[i]) {
            compLowest[++compN] = mp(2e9, 0);
            dfs(i, i);
            df = vf = 0;
            get_furthest(i, i);
            compEnds[compN].first = vf;
            int q = vf;
            df = vf = 0;
            get_furthest(q, q);
            compEnds[compN].second = vf;
        }
    }
    for (int i = 1; i <= n; i++) {
        used[i] = 0;
    }
    for (int i = 1; i <= compN; i++) {
        calc_dist(compEnds[i].first, compEnds[i].first, compEnds[i].first, 0);
        calc_dist(compEnds[i].second, compEnds[i].second, compEnds[i].second, 1);
    }
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        auto c = comp[i];
        auto d = max(distFrom[i][0], distFrom[i][1]);
        ans = max(ans, d);
        if (compLowest[c].first > d) {
            compLowest[c].first = d;
            compLowest[c].second = i;
        }
    }
    vector <int> tmp;
    for (int i = 1; i <= compN; i++) {
        tmp.pb(compLowest[i].first);
    }
    sort(tmp.rbegin(), tmp.rend());
    if (sz(tmp) > 1) {
        ans = max(ans, tmp[0]+L+tmp[1]);
    }
    if (sz(tmp) > 2) {
        ans = max(ans, tmp[1]+L+L+tmp[2]);
    }
    return ans;
}

//~ int main() {
    //~ int n, m, l;
    //~ cin >> n >> m >> l;
    //~ int x[m], y[m], t[m];
    //~ for (int i = 0; i < m; i++) {
        //~ cin >> x[i] >> y[i] >> t[i];
    //~ }
    //~ cout << travelTime(n, m, l, x, y, t);
//~ }
/*
12 8 2
0 8 4
8 2 2
2 7 4
5 11 3
5 1 7
1 3 1
1 9 5
10 6 3
*/

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