LeetCode Entry

3310. Remove Methods From Project

05.08.2026 medium 2026 kotlin rust

Remove isolated group started from K

3310. Remove Methods From Project medium substack youtube

https://dmitrysamoylenko.com/leetcode/

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Problem TLDR

Remove isolated group started from K

Intuition

Collect nodes with DFS or BFS. Then check if subgraph has any incoming edge.

Approach

• instead of the last iteration we can count in/out edges for the visited group and it is isolated if in==out

Complexity

• Time complexity: \(O(V+E)\)

• Space complexity: \(O(V+E)\)

Code

    fun remainingMethods(n: Int, k: Int, inv: Array<IntArray>)=run {
        val g = inv.groupBy({it[0]},{it[1]}); val vis = hashSetOf(k)
        fun dfs(x: Int) { g[x]?.forEach {if (vis.add(it)) dfs(it) }}
        dfs(k)
        if (inv.any{(a,b)-> b in vis&& a !in vis}) vis.clear(); (0..<n)-vis
    }

    pub fn remaining_methods(n: i32, k: i32, inv: Vec<Vec<i32>>) -> Vec<i32> {
        let (g, mut vis, mut q) = (inv.iter().map(|e| (e[0], e[1])).into_group_map(), HashSet::from([k]), vec![k]);
        while let Some(u)=q.pop() { if let Some(l) = g.get(&u) { for &v in l { if vis.insert(v) { q.push(v) }}}}
        if inv.iter().any(|e| vis.contains(&e[1]) > vis.contains(&e[0])) { vis.clear() }
        (0..n).filter(|x| !vis.contains(x)).collect()
    }