Graph Valid Tree Solution

Author: PDKhan

graph-valid-tree/PDKhan.cpp

@@ -0,0 +1,46 @@
+class Solution {
+    public:
+        bool dfs(int curr, int parent, vector<vector<int>>& graph, vector<int>& visited){
+            if(visited[curr])
+                return false;
+    
+            visited[curr] = 1;
+    
+            for(int i = 0; i < graph[curr].size(); i++){
+                if(graph[curr][i] == parent)
+                    continue;
+    
+                if(dfs(graph[curr][i], curr, graph, visited) == false)
+                    return false;
+            }
+    
+            return true;
+        }
+    
+        bool validTree(int n, vector<vector<int>> &edges) {
+            // write your code here
+            if(edges.size() != n - 1)
+                return false;
+    
+            vector<vector<int>> graph (n);
+            vector<int> visited (n, 0);
+    
+            for(int i = 0; i < edges.size(); i++){
+                int first = edges[i][0];
+                int second = edges[i][1];
+    
+                graph[first].push_back(second);
+                graph[second].push_back(first);
+            }
+    
+            if(dfs(0, -1, graph, visited) == false)
+                return false;
+            
+            for(int i = 0; i < n; i++){
+                if(visited[i] == 0)
+                    return false;
+            }
+    
+            return true;
+        }
+    };