Binary-Tree-Cameras.cpp (#53)

C++ solution for Binary Tree Cameras https://leetcode.com/problems/binary-tree-cameras/

Author: lokeshsinghi

C++/Binary-Tree-Cameras.cpp

@@ -0,0 +1,34 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+class Solution {
+public:
+    int ans=0;
+    unordered_set<TreeNode*> covered;
+    void dfs(TreeNode* root,TreeNode* parent){
+        if(root==NULL)  
+            return;
+        dfs(root->left,root);
+        dfs(root->right,root);
+        if((parent==NULL && covered.find(root)==covered.end()) || covered.find(root->left)==covered.end() || covered.find(root->right)==covered.end()){
+            ans++;
+            covered.insert(root);
+            covered.insert(parent);
+            covered.insert(root->left);
+            covered.insert(root->right);
+        }
+    }
+    int minCameraCover(TreeNode* root) {
+        covered.insert(NULL);
+        dfs(root,NULL);
+        return ans;
+    }
+};