Create 27 - Possible Bipartition.cpp

Author: sudhir5595

27 - Possible Bipartition.cpp

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+class Solution {
+public:    
+    bool isBipertite(vector < vector <int> > &graph, int src, vector <int> &visited){
+        // Create a color array to store colors  
+        // assigned to all veritces. Vertex  
+        // number is used as index in this array.  
+        // The value '-1' of colorArr[i]  
+        // is used to indicate that no color  
+        // is assigned to vertex 'i'. The value 1  
+        // is used to indicate first color  
+        // is assigned and value 0 indicates  
+        // second color is assigned. 
+        
+        vector <int> color(graph.size());
+            
+        for(int i = 0; i<color.size(); i++){
+            color[i] = -1;
+        }
+        // Assign first color to source 
+        color[src] = 1;
+        
+        queue <int> q;
+        q.push(src);
+        
+        while(!q.empty()){
+            
+            int temp = q.front();
+            visited[temp] = 1;
+            q.pop();
+            // Return false if there is a self-loop , not possible in this problem
+            if(graph[temp][temp] == 1){
+                return false;
+            }
+            // Find all non-colored adjacent vertices 
+            for(int i = 0; i<graph.size(); i++){
+                // An edge from u to v exists and destination v is not colored
+                if(graph[temp][i] && color[i] == -1){
+                    // Assign alternate color to this adjacent v of u
+                    color[i] = 1 - color[temp];
+                    q.push(i);
+                }
+        // An edge from u to v exists and destination v is colored with same color as u 
+                else if(graph[temp][i] && color[i] == color[temp]){
+                    return false;
+                }        
+            }
+        }
+        
+        return true;
+    }
+    
+    
+    bool possibleBipartition(int N, vector<vector<int>>& dislikes) {
+        vector < vector <int> > graph(N+1, vector <int> (N+1, 0));
+        for(int i = 0; i < dislikes.size(); i++){
+            int u = dislikes[i][0];
+            int v = dislikes[i][1];
+            graph[u][v] = 1;
+            graph[v][u] = 1;
+        }
+        int res = 0;
+        int src = 0;
+        vector <int> visited(N+1,0);
+        visited[0] = 1;
+        res = isBipertite(graph, 1, visited);
+        if(res == 1){
+            for(int i = 0; i<=N; i++){
+                if(visited[i] == 0){
+                 res = isBipertite(graph, i, visited);
+                }
+                if(res == 0){
+                    return 0;
+                }
+            }
+        }
+        return res;
+    }
+};