Solution

Method 1 - BFS/DFS for Suspicious Group and In-Degree Check

Intuition

The core problem is identifying suspicious methods (those reachable from the buggy method k) and determining if they can be safely removed. A suspicious method can only be removed if no non-suspicious method invokes it. We need to build both forward and reverse dependency graphs to check for external dependencies into the suspicious group.

Approach

Build adjacency lists for both forward invocations and reverse invocations (who calls whom vs. who is called by whom).
Use DFS from method k in the forward graph to identify all suspicious methods (directly or indirectly invoked by k).
Use DFS from each suspicious method in the reverse graph to find all methods that can reach suspicious methods.
If any method that can reach suspicious methods is itself not suspicious, then external dependencies exist and removal is impossible.
If no external dependencies exist, return all non-suspicious methods; otherwise, return all methods unchanged.

Code

[{"language":"C++","code":"#include <vector>\n#include <numeric>\nusing namespace std;\n\nclass Solution {\nprivate:\n    void dfs(int node, vector<bool>& visited, const vector<vector<int>>& adj) {\n        visited[node] = true;\n        for (int neighbor : adj[node]) {\n            if (!visited[neighbor]) {\n                dfs(neighbor, visited, adj);\n            }\n        }\n    }\n\npublic:\n    vector<int> remainingMethods(int n, int k, vector<vector<int>>& invocations) {\n        // Build forward and reverse adjacency lists\n        vector<vector<int>> adj(n), reverseAdj(n);\n

Related Tags