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A_star_algo.cpp
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A_star_algo.cpp
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#include <bits/stdc++.h>
#define ll long long
#define mx 1000010
using namespace std;
/***************************************************************************************/
bool visited[mx];
ll dis[mx];
ll path[mx];
ll heuristic[mx];
void A_Star(vector<pair<ll, ll>> graph[], ll source, ll destination)
{
priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>> p;
p.push({ 0 + heuristic[source], source });
dis[source] = 0;
while (!p.empty())
{
pair<ll, ll> current_node = p.top();
p.pop();
ll vertex = current_node.second;
if (visited[vertex])
{
continue;
}
else
{
visited[vertex] = true;
ll sz = graph[vertex].size();
for (ll i = 0; i < sz; i++)
{
ll child = graph[vertex][i].first;
ll weight = graph[vertex][i].second;
if (dis[vertex] + weight + heuristic[child] < dis[child])
{
dis[child] = dis[vertex] + weight + heuristic[child];
p.push({ dis[child], child });
path[child] = vertex; //in the child node always store its parent node for sortest path//
}
}
}
}
for (int i = 1; i <= destination; i++) {
cout << "sortest distance of node " << i << " is :" << dis[i] << endl;
cout << "sortest path is :";
vector<ll>ans;
ans.push_back(i);
ll temp = i;
while (path[temp] != -1)
{
ans.push_back(path[temp]);
temp = path[temp];
}
reverse(ans.begin(), ans.end());
for (ll i = 0; i < ans.size(); i++) {
cout << ans[i] << " ";
}
cout << endl << endl;
}
}
void solve()
{
vector<ll>ans;
ll numberOfTown, numberOfRoad;
cin >> numberOfTown >> numberOfRoad;
vector<pair<ll, ll>> graph[numberOfTown + 10];
for (ll i = 0; i <= numberOfTown; i++)
{
dis[i] = 1e16;
visited[i] = false;
path[i] = -1;
}
for (ll i = 0; i < numberOfRoad; i++)
{
ll u, v, wt;
cin >> u >> v >> wt;
graph[u].push_back({ v, wt });
graph[v].push_back({ u, wt });
}
A_Star(graph, 1, numberOfTown);
}
int main()
{
solve();
return 0;
}