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June 10, 2021 13:12
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>> SCC (strongly connected component) | |
>>> Resources: | |
Tutorial no.1: https://cp-algorithms.com/graph/strongly-connected-components.html | |
Tutorial no.2: https://www.youtube.com/watch?v=RpgcYiky7uw | |
>>> Implementation: | |
const ll N=200000; | |
vector<ll> adj[N],revadj[N],scc[N]; | |
stack<ll> st; | |
bool vis[N]; | |
void dfs(ll v) | |
{ | |
vis[v]=true; | |
for(auto i:adj[v]) | |
{ | |
if(!vis[i]) | |
{ | |
dfs(i); | |
st.push(i); | |
} | |
} | |
} | |
void dfs1(ll v,ll s) | |
{ | |
vis[v]=true; | |
for(auto i:revadj[v]) | |
{ | |
if(!vis[i]) | |
{ | |
dfs1(i,s); | |
scc[s].pb(i); | |
} | |
} | |
} | |
for(ll i=0;i<m;i++) | |
{ | |
ll x,y; | |
cin>>x>>y; | |
adj[x].pb(y); | |
revadj[y].pb(x); | |
} | |
for(ll i=1;i<=n;i++) | |
{ | |
if(!vis[i]) | |
{ | |
dfs(i); | |
st.push(i); | |
} | |
} | |
while(st.size()) | |
{ | |
if(!vis[st.top()]) | |
{ | |
dfs1(st.top(),st.top()); | |
} | |
else | |
{ | |
st.pop(); | |
} | |
} | |
>>> Problems: | |
Problem-1: https://codeforces.com/problemset/problem/427/C | |
Solution : https://codeforces.com/contest/427/submission/86796090 | |
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