Adding codes for Lecture 64

Lecture064 Tree Interview Questions Day2/LeftView.cpp

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+#include <bits/stdc++.h>
+using namespace std;
+
+// Tree Node
+struct Node
+{
+    int data;
+    Node* left;
+    Node* right;
+};
+
+vector<int> leftView(struct Node *root);
+
+// Utility function to create a new Tree Node
+Node* newNode(int val)
+{
+    Node* temp = new Node;
+    temp->data = val;
+    temp->left = NULL;
+    temp->right = NULL;
+
+    return temp;
+}
+
+
+// Function to Build Tree
+Node* buildTree(string str)
+{
+    // Corner Case
+    if(str.length() == 0 || str[0] == 'N')
+        return NULL;
+
+    // Creating vector of strings from input
+    // string after spliting by space
+    vector<string> ip;
+
+    istringstream iss(str);
+    for(string str; iss >> str; )
+        ip.push_back(str);
+
+    // for(string i:ip)
+    //     cout<<i<<" ";
+    // cout<<endl;
+    // Create the root of the tree
+    Node* root = newNode(stoi(ip[0]));
+
+    // Push the root to the queue
+    queue<Node*> queue;
+    queue.push(root);
+
+    // Starting from the second element
+    int i = 1;
+    while(!queue.empty() && i < ip.size()) {
+
+        // Get and remove the front of the queue
+        Node* currNode = queue.front();
+        queue.pop();
+
+        // Get the current node's value from the string
+        string currVal = ip[i];
+
+        // If the left child is not null
+        if(currVal != "N") {
+
+            // Create the left child for the current node
+            currNode->left = newNode(stoi(currVal));
+
+            // Push it to the queue
+            queue.push(currNode->left);
+        }
+
+        // For the right child
+        i++;
+        if(i >= ip.size())
+            break;
+        currVal = ip[i];
+
+        // If the right child is not null
+        if(currVal != "N") {
+
+            // Create the right child for the current node
+            currNode->right = newNode(stoi(currVal));
+
+            // Push it to the queue
+            queue.push(currNode->right);
+        }
+        i++;
+    }
+
+    return root;
+}
+
+
+int main() {
+    int t;
+    scanf("%d ",&t);
+    while(t--)
+    {
+        string s;
+        getline(cin,s);
+        Node* root = buildTree(s);
+        vector<int> vec = leftView(root);
+        for(int x : vec)
+        cout<<x<<" ";
+        cout << endl;
+    }
+    return 0;
+}
+
+// } Driver Code Ends
+
+
+/* A binary tree node
+
+struct Node
+{
+    int data;
+    struct Node* left;
+    struct Node* right;
+    
+    Node(int x){
+        data = x;
+        left = right = NULL;
+    }
+};
+ */
+
+//Function to return a list containing elements of left view of the binary tree.
+void solve(Node* root, vector<int> &ans, int level) {
+    //base case
+    if(root == NULL)
+        return ;
+
+    //we entered into a new level    
+    if(level == ans.size())
+        ans.push_back(root->data);
+
+    solve(root->left, ans, level+1);
+    solve(root->right, ans, level+1);
+}
+
+vector<int> leftView(Node *root)
+{
+   vector<int> ans;
+   solve(root, ans, 0);
+   return ans;
+}

Lecture064 Tree Interview Questions Day2/bottomView.cpp

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+#include <bits/stdc++.h>
+using namespace std;
+#define MAX_HEIGHT 100000
+
+// Tree Node
+struct Node
+{
+    int data;
+    Node* left;
+    Node* right;
+};
+
+// Utility function to create a new Tree Node
+Node* newNode(int val)
+{
+    Node* temp = new Node;
+    temp->data = val;
+    temp->left = NULL;
+    temp->right = NULL;
+
+    return temp;
+}
+
+
+vector <int> bottomView(Node *root);
+
+// Function to Build Tree
+Node* buildTree(string str)
+{
+    // Corner Case
+    if(str.length() == 0 || str[0] == 'N')
+        return NULL;
+
+    // Creating vector of strings from input
+    // string after spliting by space
+    vector<string> ip;
+
+    istringstream iss(str);
+    for(string str; iss >> str; )
+        ip.push_back(str);
+
+    // Create the root of the tree
+    Node* root = newNode(stoi(ip[0]));
+
+    // Push the root to the queue
+    queue<Node*> queue;
+    queue.push(root);
+
+    // Starting from the second element
+    int i = 1;
+    while(!queue.empty() && i < ip.size()) {
+
+        // Get and remove the front of the queue
+        Node* currNode = queue.front();
+        queue.pop();
+
+        // Get the current node's value from the string
+        string currVal = ip[i];
+
+        // If the left child is not null
+        if(currVal != "N") {
+
+            // Create the left child for the current node
+            currNode->left = newNode(stoi(currVal));
+
+            // Push it to the queue
+            queue.push(currNode->left);
+        }
+
+        // For the right child
+        i++;
+        if(i >= ip.size())
+            break;
+        currVal = ip[i];
+
+        // If the right child is not null
+        if(currVal != "N") {
+
+            // Create the right child for the current node
+            currNode->right = newNode(stoi(currVal));
+
+            // Push it to the queue
+            queue.push(currNode->right);
+        }
+        i++;
+    }
+
+    return root;
+}
+
+
+ // } Driver Code Ends
+//Function to return a list containing the bottom view of the given tree.
+
+class Solution {
+  public:
+    vector <int> bottomView(Node *root) {
+         vector<int> ans;
+        if(root == NULL) 
+        {
+            return ans;
+        }
+
+        map<int,int> topNode;
+        queue<pair<Node*, int> > q;
+
+        q.push(make_pair(root, 0));
+
+        while(!q.empty()) {
+            pair<Node*, int> temp = q.front();
+            q.pop();
+            Node* frontNode = temp.first;
+            int hd = temp.second;
+
+            topNode[hd] = frontNode -> data;
+
+            if(frontNode->left)
+                q.push(make_pair(frontNode->left, hd-1));
+            if(frontNode->right)
+                q.push(make_pair(frontNode->right, hd+1));
+        }
+
+        for(auto i:topNode) 
+        {
+            ans.push_back(i.second);
+        }
+        return ans;
+    }
+};
+
+// { Driver Code Starts.
+
+int main() {
+    int t;
+    string tc;
+    getline(cin, tc);
+    t=stoi(tc);
+    while(t--)
+    {
+        string s ,ch;
+        getline(cin, s);
+        Node* root = buildTree(s);
+        Solution ob;
+        vector <int> res = ob.bottomView(root);
+        for (int i : res) cout << i << " ";
+        cout << endl;
+    }
+    return 0;
+}
+
+
+  // } Driver Code Ends