Submission #744618

#	Time	Username	Problem	Language	Result	Execution time	Memory
744618		delrey	Dreaming (IOI13_dreaming)	C++14	0 / 100	1063 ms	9448 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;

int n, m;
int dis[100000][3];
vector < pair<int, int> > cmp;
queue < pair<int, int> > q;
vector <int> path;
vector < pair<int, int> > v[100000];

int FindFarthest(int s, int z)
{
    int ret = s;
    q.push({s, 0});
    while(q.size())
    {
        int a = q.front().first;
        int d = q.front().second;
        q.pop();
        if(dis[a][z] != -1)
            continue;
        dis[a][z] = d;
        ret = a;
        for(auto i : v[a])
            if(dis[i.first][z] == -1)
                q.push({i.first, d + i.second});
    }
    return ret;
}

int FindCenter(int s)
{
    int f1 = FindFarthest(s, 0);
    int f2 = FindFarthest(f1, 1);
    int k = f2;
    while(k != f1)
    {
        path.push_back(k);
        for(auto i : v[k])
            if(dis[i.first][1] + i.second == dis[k][1])
            {
                k = i.first;
                break;
            }
    }
    path.push_back(f1);
    int r = 0, pn = path.size(), d = dis[f2][1], delta = d;
    for(int i = 1; i < pn; i++)
    {
        int d2 = dis[path[i]][1];
        int delta2 = max(d - d2, d2) - min(d - d2, d2);
        if(delta > delta2)
        {
            delta = delta2;
            r = i;
        }
    }
    int ret = path[r];
    return ret;
}

int travelTime(int N, int M, int L, int A[], int B[], int T[])
{
    n = N;
    m = M;
    for(int i = 0; i < n; i++)
        dis[i][0] = dis[i][1] = dis[i][2] = -1;
    for(int i = 0; i < m; i++)
    {
        v[A[i]].push_back({B[i], T[i]});
        v[B[i]].push_back({A[i], T[i]});
    }
    int h = 0, cn = 0;
    for(int i = 0; i < n; i++)
    {
        if(dis[i][0] != -1)
            continue;
        int center = FindCenter(i);
        int farthest = FindFarthest(center, 2);
        cmp.push_back({center, dis[farthest][2]});
        if(cmp[h].second < cmp[cn].second)
            h = cn - 1;
        cn++;
    }
    /*
    for(auto i : cmp)
        cout<<i.first<<" "<<i.second<<endl;
    */
    int x = cmp[h].first;
    for(int i = 0; i < cn; i++)
    {
        if(i == h)
            continue;
        v[cmp[i].first].push_back({x, L});
        v[L].push_back({cmp[i].first, L});
    }
    for(int i = 0; i < n; i++)
        dis[i][0] = dis[i][1] = dis[i][2] = -1;
    int f1 = FindFarthest(0, 0);
    int f2 = FindFarthest(f1, 1);
    int res = dis[f2][1];
    return res;
}

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