[LintCode] Find the Weak Connected Component in the Directed Graph

 1 /**
 2  * Definition for Directed graph.
 3  * struct DirectedGraphNode {
 4  *     int label;
 5  *     vector<DirectedGraphNode *> neighbors;
 6  *     DirectedGraphNode(int x) : label(x) {};
 7  * };
 8  */
 9 class Solution {
10 public:
11     /**
12      * @param nodes a array of directed graph node
13      * @return a connected set of a directed graph
14      */
15     int find(unordered_map<int, int> &father, int x) {
16         if (father.find(x) == father.end()) {
17             father[x] = x;
18             return x;
19         }
20         while (x != father[x]) x = father[x];
21         return x;
22     }
23     vector<vector<int>> connectedSet2(vector<DirectedGraphNode*>& nodes) {
24         // Write your code here
25         unordered_map<int, int> father;
26         int fa, fb, fn;
27         for (auto &n : nodes) {
28             for (auto nn : n->neighbors) {
29                 fa = find(father, n->label);
30                 fb = find(father, nn->label);
31                 if (fa != fb) {
32                     if (fa > fb) father[fa] = fb;
33                     else father[fb] = fa;
34                 }
35             }
36         }
37         unordered_map<int, vector<int>> comp;
38         for (auto &n : nodes) {
39             fn = find(father, n->label);
40             comp[fn].push_back(n->label);
41         }
42         vector<vector<int>> res;
43         for (auto &c : comp) {
44             sort(c.second.begin(), c.second.end());
45             res.push_back(c.second);
46         }
47         return res;
48     }
49 };