Submission #575667

#	Time	Username	Problem	Language	Result	Execution time	Memory
575667		Mazaalai	Dreaming (IOI13_dreaming)	C++17	14 / 100	61 ms	14880 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;
    for (auto [a, b] : paths[pos]) {
        if (a == par) continue;
        int x = pre+b, y = sizes[a];
        if (max(pre, suf) > max(x, y)) return findCentroid(a, pos, pre+b);
    }
    return {pos, pre, suf};
}
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 <PII> pts;
    for (int i = 0; i < _M; i++) {
        paths[_A[i]+1].pb({_B[i]+1, _T[i]});
        paths[_B[i]+1].pb({_A[i]+1, _T[i]});
    }
    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]);
        pts.pb({point[1], point[2]});
        // cout << i-1 << ": " << point[0]-1 << ' ' << point[1] << ' ' << point[2] << '\n';
    }
    // sort(ALL(pts), [&](auto&a, auto&b) {
    //     return a.ss < b.ss;
    // });
 
    n = pts.size();
    for (int i = n-2; i >= 0; i--) {
        PII&a = pts[n-1];
        PII&b = pts[i];
        if (a.ff > a.ss) swap(a.ff, a.ss);
        if (b.ff > b.ss) swap(b.ff, b.ss);
        // cout << a.ff << ',' << a.ss << ' ' << b.ff << ',' << b.ss << " -> "; 
        VI x = {a.ff, a.ss, b.ss+L};
        VI y = {b.ff, b.ss, a.ss+L};
        sort(ALL(x));
        sort(ALL(y));
        a = {x[1], x[2]};
        b = {y[1], y[2]};
        a = max(a, b);
        // cout << a.ff << ',' << a.ss << "\n"; 
    }
    // cout << pts[n-1].ff+pts[n-1].ss << '\n';
    return pts[n-1].ff+pts[n-1].ss;
}

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