Critical Connections - Implementation

Here is the bridge-finding implementation:

function criticalConnections(n, edges):
    adj = build adjacency list from edges
    disc = array of size n, all -1
    low = array of size n, all -1
    bridges = empty list
    timer = 0

    function dfs(u, parent):
        disc[u] = timer
        low[u] = timer
        timer = timer + 1

        for v in adj[u]:
            if v == parent:
                continue
            if disc[v] == -1:
                dfs(v, u)
                low[u] = min(low[u], low[v])
                if low[v] > disc[u]:
                    bridges.append((u, v))
            else:
                low[u] = min(low[u], disc[v])

    dfs(0, -1)
    return bridges

Time: $O(V + E)$. Space: $O(V)$.