DFS+Pruning

Author: gs146

Cheapest Flights Within K Stops

@@ -0,0 +1,52 @@
+#define pb push_back
+class Solution {
+    
+     void solve(vector<vector<int>>& adj,vector<vector<int>>& cost,int src,int dst,int k,int& fare,int totCost,vector<bool>& visited)
+    {
+         if(k<-1)
+             return;
+         
+         if(src == dst)
+         {
+             fare = min(fare, totCost);
+             return;
+         }
+         
+         visited[src]=true;
+         for(int i=0;i<adj[src].size();i++)
+         {
+             if(!visited[adj[src][i]] and (totCost + cost[src][adj[src][i]]) <= fare)
+                 solve(adj, cost, adj[src][i], dst, k-1, fare, totCost+cost[src][adj[src][i]], visited);
+         }
+         visited[src] = false;
+
+    }
+    
+public:
+   
+    
+    int findCheapestPrice(int n, vector<vector<int>>& flights, int src, int dst, int K) 
+{
+    ios_base::sync_with_stdio(false);
+        cin.tie(NULL);
+        cout.tie(NULL);
+            
+        vector<vector<int>> adj(n);
+        vector<vector<int>> cost(n+1, vector<int>(n+1));
+        
+        for(int i=0;i<flights.size();i++)
+        {
+            adj[flights[i][0]].pb(flights[i][1]);
+            cost[flights[i][0]][flights[i][1]] = flights[i][2];
+        }
+        vector<bool> visited(n+1, false);
+        int fare = INT_MAX;
+        
+        solve(adj, cost, src, dst, K, fare, 0 ,visited);
+        
+        if(fare == INT_MAX)
+            return -1;
+        return fare;
+}
+    
+};