Create 1680 longestFlightRoute(optimised).cpp

Author: manitajay

cses graph/1680 longestFlightRoute(optimised).cpp

@@ -0,0 +1,96 @@
+// JAI BAJARANG BALI
+ 
+// manitianajay45
+ 
+// give me some sunshine, give me some rain, give me another chance to grow up once again....
+ 
+// sab moh maya hai....
+ 
+#include <bits/stdc++.h>
+using namespace std;
+ 
+#define ll int
+ 
+ll n, m;
+ 
+vector<ll> graph[100005];
+vector<bool> visited(100005,false);
+bool flag=false;
+vector<ll> par(100005,-1);
+vector<ll> d(100005,-1);
+ 
+ 
+void dfs(ll v){
+    
+    if(v==n){
+        flag=true;
+        d[v]=0;
+        return ;
+    }
+ 
+    
+    visited[v]=true;
+    for(auto u:graph[v]){
+      
+ 
+        
+        if(!visited[u]){
+            dfs(u);
+        }
+        if(d[u]==-1){
+            continue;
+        }
+        if(d[v]< d[u]+1){
+            d[v]=d[u]+1;
+            par[v]=u;
+        }
+ 
+        
+ 
+ 
+    }
+ 
+ 
+}
+ 
+ 
+ 
+ 
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    cin >> n >> m;
+    for(ll i=0;i<m;i++){
+        ll u,v;
+        cin>>u>>v;
+        graph[u].push_back(v);
+    }
+    d[1]=0;
+    
+ 
+    dfs(1);
+    // cout<<"-1"<<endl;
+ 
+    if(!flag){
+        cout<<"IMPOSSIBLE"<<endl;
+        return 0;
+    }
+ 
+    vector<ll> ans;
+    ll nd=1;
+    while(nd!=-1){
+        ans.push_back(nd);
+        nd=par[nd];
+    }
+    // reverse(ans.begin(),ans.end());
+    cout<<ans.size()<<endl;
+    for(auto i:ans){
+        cout<<i<<" ";
+    }
+    cout<<endl;
+ 
+   
+    
+    return 0;
+}