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Author: knockcat

0987-vertical-order-traversal-of-a-binary-tree/0987-vertical-order-traversal-of-a-binary-tree.cpp

@@ -0,0 +1,45 @@
+/**
+ * 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:
+    
+    map<int,map<int,multiset<int>>> mp;
+    
+    void helper(TreeNode* root, int id, int level)
+    {
+        if(root)
+        {
+            mp[id][level].insert(root->val);
+            helper(root->left, id-1, level + 1);
+            helper(root->right, id+1, level + 1);
+        }
+    }
+    
+    vector<vector<int>> verticalTraversal(TreeNode* root) {
+        
+        int id = 0;
+        helper(root, id, 0);
+        
+        vector<vector<int>> ans;
+        
+        for(auto&[f, s] : mp)
+        {
+            vector<int> col;
+            for(auto& ms : s)
+                col.insert(col.end(),ms.second.begin(),ms.second.end());
+            ans.push_back(col);
+        }
+        
+        return ans;
+        
+    }
+};