Submission #575769

#	Time	Username	Problem	Language	Result	Execution time	Memory
575769		Mazaalai	Dreaming (IOI13_dreaming)	C++17	14 / 100	61 ms	24844 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define ALL(x) x.begin(),x.end()
using namespace std;
using VI = vector <int>;
using PII = pair <int, int>;
const int N = 1e5+5;
vector <PII> paths[N];
bool vis[N];
int n, m, L, sizes[N], len;
PII dp[N];
 
PII getFarthest(int pos, int par = 0) {
    dp[pos] = {0, pos};
    for (auto [a, b] : paths[pos]) {
        if (a == par) continue;
        PII tmp = getFarthest(a, pos);
        if (dp[pos].ff < tmp.ff + b) dp[pos] = {tmp.ff + b, tmp.ss};
    }
    return dp[pos];
}
int getSizes(int pos, int par = 0) {
    vis[pos] = 1;
    for (auto [a, b] : paths[pos]) {
        if (a == par) continue;
        sizes[pos] = max(sizes[pos], b + getSizes(a, pos));
    }
    return sizes[pos];
}
VI findCentroid(int pos, int par = 0, int pre = 0) {
    int suf = len - pre;
    VI res = {pos, pre, suf};
    for (auto [a, b] : paths[pos]) {
        if (a == par) continue;
        VI tmp = findCentroid(a, pos, pre+b);
        if (max(pre, suf) > max(tmp[1], tmp[2])) res = tmp;
    }
    return res;
}
VI getCentroid(int pos) {
    len = getSizes(pos);
    return findCentroid(pos);
}
int travelTime(int _N, int _M, int _L, int _A[], int _B[], int _T[]) {
    n = _N;
    m = _M;
    L = _L;
    vector <int> pts = {-1, -1, -1};
    for (int i = 0; i < _M; i++) {
        // paths[_A[i]].pb({_B[i], _T[i]});
        // paths[_B[i]].pb({_A[i], _T[i]});
        paths[_A[i]+1].pb({_B[i]+1, _T[i]});
        paths[_B[i]+1].pb({_A[i]+1, _T[i]});
    }
    int res = 0;
    for (int i = 1; i <= n; i++) {
        if (vis[i]) continue;
        PII tmp = getFarthest(i);
        VI point = getCentroid(tmp.ss);
        if (point[1] < point[2]) swap(point[1], point[2]);
         // cout << '\t';for (int i = 0; i < 3; i++) cout << point[i] << " \n"[i==2];
        pts[0] = (max(point[1], point[2]));
        res = max(res, point[1]+point[2]);
        sort(ALL(pts));
        // cout << i-1 << ": " << point[0]-1 << ' ' << point[1] << ' ' << point[2] << '\n';
        // cout << i << ": " << point[0] << ' ' << point[1] << ' ' << point[2] << '\n';
    }
    // for (int i = 0; i < 3; i++) cout << pts[i] << " \n"[i==2];
    res = max(res, pts[2]+pts[1]+L);
    if (pts[0] != -1) {
        int tmp = max(pts[0], pts[1]+pts[2]+2*L);
        res = max(res, tmp);
    }  
    // cout << res << '\n';
    return res;
}

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