Merge pull request #714 from gargsahaj/master

Bottom View of Binary Tree

Trees Algorithm/Bottom_View_of_Binary_Tree.cpp

@@ -0,0 +1,142 @@
+// { Driver Code Starts
+#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) {
+ // Your Code Here
+ vector<int>ans;
+ if(root==NULL)return ans;
+ map<int,int>mp;
+ queue<pair<Node*,int>>q;
+ q.push({root,0});
+ while(!q.empty()){
+ auto it = q.front();
+ q.pop();
+ int level = it.second;
+ Node* node = it.first;
+ mp[level] = node->data;
+ if(node->left)q.push({node->left,level-1});
+ if(node->right)q.push({node->right,level+1});
+ }
+ for(auto it:mp){
+ ans.push_back(it.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