A* Search Algorithm

Author: amitbansal7

10.Graphs/AStarSearchAlgorithm.cpp

@@ -0,0 +1,78 @@
+/* Amit Bansal - amitbansal7 */
+#include <bits/stdc++.h>
+using namespace std;
+
+void AStar(vector<pair<int, pair<int, int> > >adj[], int src, int dest, int heuristicDistFromSource, int v)
+{
+	priority_queue< pair<int, int>, vector<pair<int, int> >, greater<pair<int, int> > > pq;
+
+	vector<int> dist(v, INT_MAX);
+	vector<int> parent(v, -1);
+
+	parent[src] = src;
+	dist[src] = 0;
+
+	pq.push(make_pair(dist[src] + heuristicDistFromSource, src));
+
+	while (!pq.empty())
+	{
+		int u = pq.top().second;
+		pq.pop();
+
+		if (u == dest)
+			break;
+
+		vector<pair<int, pair<int, int> > >::iterator it;
+		for (it = adj[u].begin(); it != adj[u].end(); it++)
+		{
+			int v = it->first;
+			int w = it->second.first;
+			int heuristic = it->second.second;
+
+			if (dist[v] > dist[u] + w)
+			{
+				dist[v] = dist[u] + w;
+				pq.push(make_pair(dist[v] + heuristic, v));
+				parent[v] = u;
+			}
+		}
+	}
+
+	cout << "Distance from " << src << " to " << dest << " is " << dist[dest] << endl;
+	cout << "Path is " << dest;
+	int p = dest;
+	while (parent[p] != p)
+	{
+		cout << "<-" << parent[p];
+		p = parent[p];
+	}
+	cout << endl;
+}
+
+int main()
+{
+	vector<pair<int, pair<int, int> > >adj[13];
+
+	//adj[src].push_back(make_pair(dest, make_pair(weight, heuristic)));
+	adj[0].push_back(make_pair(1, make_pair(7, 9)));
+	adj[0].push_back(make_pair(2, make_pair(2, 7)));
+	adj[0].push_back(make_pair(3, make_pair(3, 8)));
+	adj[1].push_back(make_pair(2, make_pair(3, 7)));
+	adj[1].push_back(make_pair(4, make_pair(0, 10)));
+	adj[2].push_back(make_pair(4, make_pair(4, 8)));
+	adj[2].push_back(make_pair(8, make_pair(1, 6)));
+	adj[3].push_back(make_pair(12, make_pair(2, 6)));
+	adj[4].push_back(make_pair(6, make_pair(5, 6)));
+	adj[7].push_back(make_pair(5, make_pair(2, 0)));
+	adj[8].push_back(make_pair(7, make_pair(2, 3)));
+	adj[8].push_back(make_pair(6, make_pair(3, 6)));
+	adj[9].push_back(make_pair(10, make_pair(6, 4)));
+	adj[9].push_back(make_pair(11, make_pair(4, 3)));
+	adj[10].push_back(make_pair(11, make_pair(4, 3)));
+	adj[11].push_back(make_pair(5, make_pair(5, 0)));
+	adj[12].push_back(make_pair(9, make_pair(6, 4)));
+	adj[12].push_back(make_pair(10, make_pair(4, 4)));
+
+	// AStar(adj, src, dest, heuristicDistFromSource, nmberOfEdges);
+	AStar(adj, 0, 5, 10, 13);
+}