update

Author: yashsiwach

CP Templetes/Graphs/BFS.cpp

@@ -24,4 +24,4 @@ void bfs(int firstnode, unordered_map<int, bool>& visited)
 // if(!visited[i]) {
 // g.bfs(i, visited);
 // }
-// }
+// } 

CP Templetes/Graphs/cycle detection dfs directed.cpp

@@ -0,0 +1,80 @@
+#include <bits/stdc++.h>
+using namespace std;
+#ifdef ONLINE_JUDGE
+#define DISABLE_STACK_SIZE_CHANGE
+#endif
+#ifndef DISABLE_STACK_SIZE_CHANGE
+#include <sys/resource.h>
+#endif
+typedef long long ll;
+const ll MOD = 1000000007;
+#define pb push_back
+#define ff first
+#define ss second
+#define nl "\n"
+#define set_bits(x) __builtin_popcountll(x)
+#define all(x) (x).begin(), (x).end()
+#define debug(x) cerr<<#x<<" "<<x<<endl;
+#define loop(i,a,b) for(int i=(a);i<(b);i++)
+#define print(x) for(auto it:(x)) cout<<(it)<<" "; cout<<endl;
+#define showadj for (auto it : adj) { cout << it.ff << " ->"; for (auto i : it.ss) cout << i << " "; cout << endl; }
+template<typename T> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }
+template<typename T> T binpow(T base,T power,T mod){ ll ans=1; base = base % mod;while(power){if(power&1) ans=(ans*base)%mod; base=((base*base)%mod); power>>=1;}return ans;}
+
+bool dfs(int node,unordered_map<int,bool>&visi,unordered_map<int,vector<int>>&adj,int parent,unordered_map<int,bool>&dfsvisi)
+{
+ visi[node]=true;
+ dfsvisi[node]=true;
+ for(auto nbr:adj[node])
+ {
+ if(!visi[nbr])
+ {
+ bool ans=dfs(nbr,visi,adj,node,dfsvisi);
+ if(ans)return true;
+ }
+ else 
+ {
+ if(dfsvisi[nbr])return true;
+ }
+ }
+ dfsvisi[node]=false;
+ return false;
+}
+
+int main()
+{
+ ios_base::sync_with_stdio(0);cin.tie(0);
+ #ifndef DISABLE_STACK_SIZE_CHANGE
+ rlimit rlim;
+ if (getrlimit(RLIMIT_STACK, &rlim) != 0) {return 1;}
+ rlim.rlim_cur = 1024 * 1024 * 1024;
+ if (setrlimit(RLIMIT_STACK, &rlim) != 0) {return 2;}
+ #endif
+
+ int n;
+ cin>>n;
+ unordered_map<int,vector<int>>adj;
+ unordered_map<int,bool>visi;
+ unordered_map<int,bool>dfsvisi;
+ loop(i,0,n)
+ {
+ int u,v;
+ cin>>u>>v;
+ adj[u].pb(v);
+ }
+ loop(i,0,n+1)
+ {
+ if(!visi[i])
+ {
+ bool ans=dfs(i,visi,adj,0,dfsvisi);
+ if(ans)
+ {
+ cout<<"cycle"<<endl;
+ return 0;
+ break;
+ }
+ }
+ }
+ cout<<"no"<<endl;
+}
+

Important.txt

@@ -14,4 +14,10 @@
 14->int sum=accumulate(v.begin(),v.end(),0(initial sum value)); to get sum of vector;
 15-> transform(s.begin(), s.end(), s.begin(), ::tolower); to make string lower ;
 sweepline adhoc 
-16->s.erase(unique(s.begin(), s.end()), s.end()); to remove all duplicates of string or vector;
+16->s.erase(unique(s.begin(), s.end()), s.end()); to remove all duplicates of string or vector;
+17->print 
+vector<pair<int, int>> e(n);
+for (auto [x, y]: e) {
+ cerr << x << ' ' << y << '\n';
+}
+cerr << '\n';