Kosaraju's Algo for Strongly connected components

Graphs/kosaraju.cpp

@@ -0,0 +1,86 @@
+#include<bits/stdc++.h>
+#define int long long
+#define pb emplace_back
+#define mp make_pair
+#define tci(v,i) for(auto i=v.begin();i!=v.end();i++)
+#define all(v) v.begin(),v.end()
+#define rep(i,start,lim) for(long long (i)=(start);i<(lim);i++)
+#define revrep(i,n) for(long long i=n-1;i>=0;i--)
+#define boost ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
+#define osit ostream_iterator<int> output (cout," ")
+#define pv(x) copy(all(x),output)
+#define pa(a) rep(i,0,sizeof(a)/sizeof(a[0]))cout<<a[i]<<" "
+#define endl '\n'
+#define f first
+#define s second
+#define PI 3.141592653589793
+#define set0(x) memset(x,0,sizeof(x))
+#define set1(x) memset(x,1,sizeof(x))
+#define getarr(arr,n) int arr[n];rep(i,0,n)cin>>a[i]
+#define getvec(vec,n) vi vec;int x;rep(i,0,n){cin>>x;vec.pb(x);}
+#define sort_uniq(c) (sort(c.begin(), c.end()), c.resize(distance(c.begin(), unique(c.begin(), c.end()))))
+#define uniq(a) a.resize(distance(a.begin(), unique(a.begin(), a.end())))
+#define dg(x) cout<<#x<<':'<<x<<endl;
+#define dg2(x,y) cout<<#x<<':'<<x<<' '<<#y<<':'<<y<<endl;
+#define dg3(x,y,z) cout<<#x<<':'<<x<<' '<<#y<<':'<<y<<' '<<#z<<':'<<z<<endl;
+#define dg4(x,y,z,zz) cout<<#x<<':'<<x<<' '<<#y<<':'<<y<<' '<<#z<<':'<<z<<' '<<#zz<<':'<<zz<<endl;
+using namespace std;
+typedef vector<int> vi;
+typedef pair<int,int> ii;
+typedef vector<ii> vii;
+template<typename T> T gcd(T a,T b){if(a==0) return b; return gcd(b%a,a);}
+int isPowerof2(int x) { return (x && !(x & x-1)); }
+
+vi adj[100];
+int visited[100];
+stack<int> st;
+
+void dfs1(int s){
+	visited[s]=1;
+	for(auto x:adj[s]){
+		if(!visited[x])dfs1(x);
+	}
+	st.push(s);
+}
+
+void dfs2(int s){
+	visited[s]=1;
+	cout<<s<<" ";
+	for(auto x:adj[s]){
+		if(!visited[x])dfs2(x);
+	}
+}
+
+int32_t main(){
+	boost;
+	int n,m;
+	cin>>n>>m;
+	vii t;
+	rep(i,0,m){
+		int x,y;
+		cin>>x>>y;
+		t.pb(mp(x,y));
+		adj[x].pb(y);
+	}
+	rep(i,1,n+1){
+		if(!visited[i]){
+			dfs1(i);
+		}
+	}
+	rep(i,0,100){
+		adj[i].clear();
+	}
+	set0(visited);
+	rep(i,0,m){
+		adj[t[i].s].pb(t[i].f);
+	}
+	while(!st.empty()){
+		int el=st.top();
+		st.pop();
+		if(!visited[el]){
+			dfs2(el);
+			cout<<endl;
+		}
+	}
+	return 0;
+}