# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1057049 | fv3 | Roller Coaster Railroad (IOI16_railroad) | C++14 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "shortcut.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
vector<vector<pair<int, ll>>> adj;
int N;
vector<int> visited;
vector<ll> dist;
ll find_diameter()
{
visited = vector<int>(N);
dist = vector<ll>(N, 1ll << 60);
priority_queue<pair<ll, int>> q;
q.push({0, 0});
dist[0] = 0;
int mx_index;
while (1)
{
int s = q.top().second;
q.pop();
visited[s] = 1;
for (auto node : adj[s])
{
if (visited[node.first] || dist[s] + node.second > dist[node.first]) continue;
dist[node.first] = dist[s] + node.second;
q.push({-dist[node.first], node.first});
}
if (q.empty())
{
mx_index = s;
break;
}
}
visited = vector<int>(N);
dist = vector<ll>(N, 1ll << 60);
q.push({0, mx_index});
dist[mx_index] = 0;
while (1)
{
int s = q.top().second;
q.pop();
visited[s] = 1;
for (auto node : adj[s])
{
if (visited[node.first] || dist[s] + node.second > dist[node.first]) continue;
dist[node.first] = dist[s] + node.second;
q.push({-dist[node.first], node.first});
}
if (q.empty())
{
return dist[s];
}
}
return 0;
}
ll find_shortcut(int n, std::vector<int> l, std::vector<int> d, int c)
{
N = 2 * n;
adj.resize(N);
for (int i = 0; i < n - 1; i++)
{
adj[i].push_back({i+1, l[i]});
adj[i+1].push_back({i, l[i]});
}
for (int i = 0; i < n; i++)
{
adj[i].push_back({i+n, d[i]});
adj[i+n].push_back({i, d[i]});
}
ll res = 1ll << 60;
for (int i = 0; i < n - 1; i++)
{
for (int j = i+1; j < n; j++)
{
adj[i].push_back({j, c});
adj[j].push_back({i, c});
res = min(res, find_diameter());
adj[i].pop_back();
adj[j].pop_back();
}
}
return res;
}