Vertical_Traversal

algorithms/CPlusPlus/Trees/Vertical_Order.cpp

@@ -0,0 +1,43 @@
+class Solution
+{
+    public:
+    //Function to find the vertical order traversal of Binary Tree.
+    vector<int> verticalOrder(Node *root)
+    {
+        //Your code here
+        list<pair<int,Node*>>l;//queue having hd and node
+        map<int,vector<int>>mp;// a vertical level mapped to ele in that level
+        vector<int>ans;//ans vector
+        if(!root)return ans;
+        l.push_back({0,root});
+        while(!l.empty()){
+            
+            pair<int,Node*>p=l.front();
+            //frst is hd and second is node
+            mp[p.first].push_back(p.second->data);//map data to the vertical level it belongs to 
+            if(p.second->left)l.push_back({p.first-1,p.second->left});//hd=current-1 for left
+            if(p.second->right)l.push_back({p.first+1,p.second->right});//hd=current +1 for right
+            l.pop_front();
+        }
+        // now map has elements acc to level
+        // make a vector each for a level
+        //push that vector to ans vector
+        
+        /* map looks like this
+                   frst     snd
+           begin:  (-1)->  [9]
+           begin+1: (0)->  [3,15]
+           begin+2: (1)->  [20]
+           begin+3: (2)->  [7]       */
+        for(auto it=mp.begin();it!=mp.end();it++){
+            pair<int,vector<int>>q=*it;
+            int size=q.second.size();
+            vector<int>level;
+            for(int i=0;i<size;i++){
+                ans.push_back(q.second[i]);
+            }
+            //ans.push_back(level);
+        }
+        return ans;
+    }
+};