Update 924.Minimize-Malware-Spread.cpp

Union_Find/924.Minimize-Malware-Spread/924.Minimize-Malware-Spread.cpp

@@ -1 +1,69 @@
-
+class Solution {
+    unordered_map<int,int>Root;
+public:
+    int minMalwareSpread(vector<vector<int>>& graph, vector<int>& initial) 
+    {
+        int N = graph.size();
+        for (int i=0; i<N; i++) 
+            Root[i] = i;
+        for (int i=0; i<N; i++)
+            for (int j=0; j<N; j++)
+            {
+                if (i==j) continue;
+                if (graph[i][j]==0) continue;
+                if (findRoot(i)!=findRoot(j))
+                    Union(i,j);
+            }
+
+        unordered_map<int,vector<int>>Children;
+        for (int i=0; i<N; i++)
+        {
+            Root[i] = findRoot(i);
+            Children[Root[i]].push_back(i);
+        }
+
+        set<int>Set(initial.begin(),initial.end());
+
+        int MaxGroup = 0;        
+        int result;
+        for (auto a:Children)
+        {
+            int count = 0;
+            int candidate;
+            for (auto b:a.second)
+            {
+                if (Set.find(b)!=Set.end())
+                {
+                    count++;
+                    candidate = b;
+                }                    
+                if (count>1) break;
+            }
+            if (count==1 && (a.second.size()>MaxGroup || a.second.size()==MaxGroup && candidate<result))
+            {
+                MaxGroup = a.second.size();
+                result = candidate;
+            }
+        }
+
+        if (MaxGroup!=0) return result;
+        else return *Set.begin();
+    }
+
+    int findRoot(int x)
+    {
+        if (Root[x]!=x)
+            Root[x] = findRoot(Root[x]);
+        return Root[x];
+    }
+
+    void Union(int x, int y)
+    {
+        x = Root[x];
+        y = Root[y];
+        if (x<y) 
+            Root[y] = x;
+        else
+            Root[x] = y;
+    }
+};