71 lines
1.9 KiB
C++
71 lines
1.9 KiB
C++
#include <iostream>
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#include <vector>
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#include <queue>
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using namespace std;
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const int INF = 1e9;
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vector<vector<pair<int, int>>> adj;
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vector<int> dist;
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vector<bool> vis;
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vector<vector<int>> path;
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priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
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bool lessthan(vector<int> a, vector<int> b) {
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for(int i = 0; i < min(a.size(), b.size()); i++) {
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if(a[i] < b[i]) return true;
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if(a[i] > b[i]) return false;
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}
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return a.size() < b.size();
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}
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int main() {
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int n, m;
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cin >> n >> m;
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adj.resize(n + 1);
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dist.resize(n + 1, INF);
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vis.resize(n + 1, false);
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path.resize(n + 1);
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for(int i = 0; i < m; i++) {
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int a, b, c;
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cin >> a >> b >> c;
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adj[a].push_back(make_pair(b, c));
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}
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dist[0] = 0;
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path[0].push_back(0);
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pq.push(make_pair(0, 0));
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while(!pq.empty()) {
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int u = pq.top().second;
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pq.pop();
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if(vis[u]) continue;
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vis[u] = true;
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for(auto [v, w] : adj[u]) {
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if(dist[v] > dist[u] + w) {
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dist[v] = dist[u] + w;
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path[v] = path[u];
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path[v].push_back(v);
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pq.push(make_pair(dist[v], v));
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}
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else if(dist[v] == dist[u] + w) {
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vector<int> new_path = path[u];
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new_path.push_back(v);
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if(path[v].empty() || path[v].size() > new_path.size() ||
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(path[v].size() == new_path.size() && lessthan(new_path, path[v]))) {
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path[v] = new_path;
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pq.push(make_pair(dist[v], v));
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}
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}
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}
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}
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for(int i = 1; i < n; i++) {
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if(dist[i] != INF && !path[i].empty()) {
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for(int j = 0; j < path[i].size(); j++) {
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if(j > 0) cout << "->";
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cout << path[i][j];
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}
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cout << endl;
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}
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}
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return 0;
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} |