Create 1751-PlanetsCycles.cpp

steps:-
1. firstly try to find out a cycle and its length then assign every node value equal to cycle length.
2. after that start traverse back to eveynodes parent and ans[par]=ans[child]+1; if(ans[par] not find before);

3. there would be one more case if we traversing node and we have already ans of a child then we started to traverse back from there:
  ans[par]=ans[child]+1; if(ans[par] not find before);

Author: manitajay

cses graph/1751-PlanetsCycles.cpp

@@ -0,0 +1,119 @@
+// 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:-
+1. firstly try to find out a cycle and its length then assign every node value equal to cycle length.
+2. after that start traverse back to eveynodes parent and ans[par]=ans[child]+1; if(ans[par] not find before);
+
+3. there would be one more case if we traversing node and we have already ans of a child then we started to traverse back from there:
+  ans[par]=ans[child]+1; if(ans[par] not find before);
+  
+*/
+
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define ll long long
+#define mod 1000000007
+ll n;
+
+
+vector<ll> graph[200005];
+vector<ll> visited(200005,0);
+vector<ll> par(200005,-1);
+vector<pair<ll,bool>> ans(200005,{0,false});
+ll cl=1;
+void dfs(ll v){
+    visited[v]=cl;
+    for(auto u:graph[v]){
+        if(visited[u]==0){
+            par[u]=v;
+            dfs(u);
+        }
+
+        if(visited[u]==cl){
+            ll st=v;
+            ll cyc=0;
+            while(st!=u){
+                cyc++;
+                st=par[st];
+            }
+            st=v;
+            cyc++;
+            while(st!=u){
+                ans[st].first=cyc;
+                st=par[st];
+            }
+            // cyc++;
+            ans[st].first=cyc;
+            ans[st].second=true;
+            ll prev=st;
+            while(st!=-1){
+                prev=st;
+                st=par[st];
+                if(!ans[st].second){
+                    ans[st].first=ans[prev].first+1;
+                    ans[st].second=true;
+                }
+            }
+        }else if(visited[u]!=(-1*cl)){
+            // cout<<"UES"<<endl;
+            // cout<<u<<endl;
+            ll st=v;
+            ll prev=u;
+            while(st!=-1 ){
+                if(!ans[st].second){
+                    ans[st].first=ans[prev].first+1;   
+                    ans[st].second=true;
+                } 
+                prev=st;
+                st=par[st];            
+            }
+            
+            
+        }
+    }
+    visited[v]=(-1*cl);
+}
+
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+
+    // ll n;
+    cin >> n;
+
+    for (ll i = 1; i <=n; i++)
+    {
+        ll x;
+        cin>>x;
+        
+        graph[i].push_back(x);
+    }   
+    for(ll i=1;i<=n;i++){
+        if(visited[i]==0){
+            dfs(i);
+            cl++;
+        }
+    }
+
+
+    for(ll i=1;i<=n;i++){
+        cout<<ans[i].first<<" ";
+    }
+    cout<<endl;
+
+
+
+    return 0;
+}