From 1084b13f3d77752e2eadb29726e0ebe0d4c0334b Mon Sep 17 00:00:00 2001
From: Deepak Singh <deepak0064.cse19@chitkara.edu.in>
Date: Mon, 4 Oct 2021 01:38:35 +0530
Subject: [PATCH] Added Vertical Order Traversal of a Binary Tree (LeetCode)

---
 VerticalOrderTraversal.cpp | 71 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 VerticalOrderTraversal.cpp

diff --git a/VerticalOrderTraversal.cpp b/VerticalOrderTraversal.cpp
new file mode 100644
index 0000000..74c36a0
--- /dev/null
+++ b/VerticalOrderTraversal.cpp
@@ -0,0 +1,71 @@
+// Vertical Order Traversal of a Binary Tree (LeetCode)
+// Difficulty - Hard
+//https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/
+
+class Solution
+{
+public:
+    vector<vector<int>> verticalTraversal(TreeNode *root)
+    {
+        vector<vector<int>> ans;
+        if (root == NULL)
+            return ans;
+        map<int, map<int, vector<int>>> m;
+        queue<pair<TreeNode *, pair<int, int>>> q;
+
+        pair<TreeNode *, pair<int, int>> roo;
+        roo.first = root;
+        roo.second.first = 0;
+        roo.second.second = 0;
+
+        q.push(roo);
+        while (!q.empty())
+        {
+            pair<TreeNode *, pair<int, int>> p = q.front();
+            q.pop();
+
+            m[p.second.first][p.second.second].push_back(p.first->val);
+            // cout<<p.second.second<<endl;
+
+            if (p.first->left)
+            {
+                pair<TreeNode *, pair<int, int>> pp;
+                pp.first = p.first->left;
+                pp.second.first = p.second.first - 1;
+                pp.second.second = p.second.second + 1;
+
+                q.push(pp);
+            }
+            if (p.first->right)
+            {
+                pair<TreeNode *, pair<int, int>> pp;
+                pp.first = p.first->right;
+                pp.second.first = p.second.first + 1;
+                pp.second.second = p.second.second + 1;
+
+                q.push(pp);
+            }
+        }
+
+        map<int, map<int, vector<int>>>::iterator itr;
+
+        for (itr = m.begin(); itr != m.end(); ++itr)
+        {
+
+            vector<int> a;
+            map<int, vector<int>>::iterator itrr;
+            for (itrr = itr->second.begin(); itrr != itr->second.end(); ++itrr)
+            {
+                sort(itrr->second.begin(), itrr->second.end());
+                for (int i = 0; i < itrr->second.size(); i++)
+                {
+                    a.push_back(itrr->second[i]);
+                }
+            }
+
+            ans.push_back(a);
+        }
+
+        return ans;
+    }
+};
\ No newline at end of file