Create 1686 Coin Collector.cpp

firstly merge all the strongly connected components and now graph is DAG can find max value of traversable nodes using dp .

Author: manitajay

cses graph/1686 Coin Collector.cpp

@@ -0,0 +1,134 @@
+// 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....
+
+/*
+steps:-
+
+firstly merge all the strongly connected componenets and now graph is DAG .
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define ll long long
+#define mod 1000000007
+ll n,m;
+
+vector<bool> visited(200005,false);
+vector<ll> graph[200005];
+vector<ll> order;
+vector<ll> graphr[200005];
+set<ll> gph[200005];
+vector<ll> vis(200005,0);
+vector<ll> vec(200005,0);
+
+ll an=0;
+ll weight[200005];
+ll val=0;
+
+vector<ll> ans(200005,-1);
+
+
+void topo(ll v){
+    visited[v]=true;
+    for(auto u:graph[v]){
+        if(!visited[u]){
+            topo(u);
+        }
+    }
+    order.push_back(v);
+}
+bool flag=true;
+
+void dfs(ll v){
+//    cout<<v<<" ";
+    vis[v]=an;
+    val+=weight[v];
+    for(auto u:graphr[v]){
+        if(vis[u]==0){
+            dfs(u);
+        }else if(vis[u]!=an){
+            gph[vis[u]].insert(an);
+        }
+        
+    }
+
+}
+
+
+ll mx=0;
+
+ll ansfunc(ll v){
+    if(ans[v]!=-1){
+        return ans[v];
+    }
+    visited[v]=true;
+    ans[v]=vec[v];
+    for(auto u:gph[v]){
+        // if(!visited[u]){
+            ans[v]=max(ans[v],vec[v]+ansfunc(u));
+        // }
+    }
+    return ans[v];
+}
+
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+
+    // ll n;
+    cin >> n>>m;
+
+    for(ll i=1;i<=n;i++){
+        cin>>weight[i];
+    }
+
+    vector<pair<ll,ll>> edges;
+
+    for (ll i = 0; i < m; i++)
+    {
+        ll u,v;
+        cin>>u>>v;
+        graph[u].push_back(v);
+        graphr[v].push_back(u);
+        edges.push_back({u,v});
+       
+    }
+    for(ll i=1;i<=n;i++){
+        if(!visited[i]){
+            topo(i);
+        }
+    }
+
+    reverse(order.begin(),order.end());
+
+    // vec.push_back(0);
+    for(auto i:order){
+        if(vis[i]==0){
+            an++;
+            val=0;
+            dfs(i);
+            vec[an]=val;
+        
+        }
+    }
+    
+    for(ll i=1;i<=an;i++){
+        if(ans[i]==-1){
+            // cout<<i<<" ";
+            mx=max(mx,ansfunc(i));
+            // cout<<ansfunc(i)<<endl;````````````````````
+        }
+    }
+    cout<<mx<<endl;
+    
+
+    return 0;
+}