| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 557209 | Olympia | Dreaming (IOI13_dreaming) | C++17 | 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 <iostream>
#include <vector>
#include "dreaming.h"
#include <climits>
#include <queue>
#include <map>
#include <algorithm>
using namespace std;
vector<int> a, b, w;
vector<vector<int> > adj;
map<pair<int,int>,int> myMap;
vector<bool> hasVisited;
vector<int> parent;
pair<int,int> find_farthest_node (int x, bool undo) {
queue<pair<int,int> > q;
q.push(make_pair(x, 0));
hasVisited[x] = true;
parent[x] = -1;
vector<int> nodes;
vector<pair<int,int> > vec;
while (!q.empty()) {
pair<int,int> p = q.front();
nodes.push_back(p.first);
vec.push_back(make_pair(p.second, p.first));
q.pop();
for (int j: adj[p.first]) {
if (!hasVisited[j]) {
q.push(make_pair(j, p.second + myMap[make_pair(j, p.first)]));
parent[j] = p.first;
hasVisited[j] = true;
}
}
}
if (undo) {
for (int j: nodes) {
hasVisited[j] = false;
}
}
sort(vec.begin(), vec.end());
return vec.back(); //first distance, then node
}
int travelTime (int N, int M, int L, int A[], int B[], int W[]) {
a.resize(M), b.resize(M), w.resize(M), adj.resize(N), parent.resize(N);
for (int i = 0; i < M; i++) {
a[i] = A[i], b[i] = B[i], w[i] = W[i];
myMap[make_pair(a[i], b[i])] = w[i];
myMap[make_pair(b[i], a[i])] = w[i];
adj[a[i]].push_back(b[i]), adj[b[i]].push_back(a[i]);
}
hasVisited.assign(N, false);
vector<int> paths;
int ans = 0;
for (int i = 0; i < N; i++) {
if (!hasVisited[i]) {
int x = find_farthest_node(i, true).second;
pair<int,int> py = find_farthest_node(x, false).second;
vector<int> nodes;
int val = y;
while (val != -1) {
nodes.push_back(val);
val = parent[val];
}
ans = max(ans, py.first);
int c = 0;
int myMin = INT_MAX;
for (int j = 1; j < (int)nodes.size(); j++) {
c += myMap[make_pair(nodes[j], nodes[j - 1])];
myMin = min(myMin,max(c, py.first - c));
}
if (nodes.size() == 1) {
myMin = 0;
}
paths.push_back(myMin);
}
}
sort(paths.begin(), paths.end());
//cout << paths.size() << '\n';
if (paths.size() == 1) {
ans = max(ans, paths[0]);
} else if (paths.size() == 2) {
ans = max(paths.back() + paths[paths.size() - 2] + L, ans);
} else {
ans = max(paths.back() + paths[paths.size() - 2] + 2 * L, ans);
}
return ans;
}
/*
int main() {
int N = 12;
int M = 8;
int L = 2;
int A[M], B[M], T[M];
A[0] = 0, A[1] = 8, A[2] = 2, A[3] = 5, A[4] = 5, A[5] = 1, A[6] = 1, A[7] = 10;
B[0] = 8, B[1] = 2, B[2] = 7, B[3] = 11, B[4] = 1, B[5] = 3, B[6] = 9, B[7] = 6;
T[0] = 4, T[1] = 2, T[2] = 4, T[3] = 3, T[4] = 7, T[5] = 1, T[6] = 5, T[7] = 3;
cout << travelTime(N, M, L, A, B, T);
}
*/