Create 785.Is-Graph-Bipartite.cpp

Yifan-Zhao · Sep 16, 2019 · 14c9e15 · 14c9e15
1 parent 4c4b1a2
commit 14c9e15
Showing 1 changed file with 42 additions and 0 deletions.
diff --git a/BFS/785.Is-Graph-Bipartite/785.Is-Graph-Bipartite.cpp b/BFS/785.Is-Graph-Bipartite/785.Is-Graph-Bipartite.cpp
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+class Solution {
+public:
+    bool isBipartite(vector<vector<int>>& graph) 
+    {
+        int n = graph.size();
+        vector<int>visited(n,-1);
+
+        for (int i=0; i<n; i++)
+        {
+            if (visited[i]!=-1)
+                continue;
+
+            queue<pair<int,int>>q;
+            q.push({i,0}); // {node, group}
+            visited[i] = 0;
+
+            while (!q.empty())
+            {
+                int node = q.front().first;
+                int group = q.front().second;
+                q.pop();
+
+                for (auto next: graph[node])
+                {                   
+
+                    if (visited[next]!=-1)
+                    {
+                        if (visited[next]!=1-group)
+                            return false;
+                    }
+                    else
+                    {
+                        visited[next] = 1-group;                
+                        q.push({next, 1-group});
+                    }
+                }
+            }        
+        }
+
+        return true;        
+    }
+};