Longest consecutive sequence in a binary tree

Author: spaceman-dev

Some_More_Trees/LongestConsecutiveSequenceInBinaryTree.cpp

@@ -0,0 +1,142 @@
+// { Driver Code Starts
+#include <bits/stdc++.h>
+using namespace std;
+
+// 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;
+}
+
+// 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
+/*
+struct Node
+{
+int data;
+Node *left, *right;
+};
+*/
+class Solution
+{
+ public:
+ // your task is tp complete this function
+ // function should return the length of the longestConsecutive
+ // sequence
+ void longestConsecutiveSequence(Node* root, int count, int prevVal, int &res)
+ {
+ if(!root)
+ return;
+ if(root->data == prevVal + 1)
+ {
+ count++;
+ res = max(res, count);
+ }
+ else
+ count = 1;
+ longestConsecutiveSequence(root->left, count, root->data, res);
+ longestConsecutiveSequence(root->right, count, root->data, res);
+ }
+ int longestConsecutive(Node* root)
+ {
+ //Code here
+ int res = 1, prevVal = root->data, count = 1;
+ longestConsecutiveSequence(root, count, prevVal, res);
+ return res == 1 ? -1 : res;
+ }
+};
+
+// { Driver Code Starts.
+int main()
+{
+ int t;
+ cin>>t;
+ getchar();
+ while (t--)
+ {
+ string s;
+ getline(cin,s);
+ Node* root = buildTree(s);
+ Solution obj;
+ cout<<obj.longestConsecutive(root)<<endl;
+ }
+ return 0;
+}
+ // } Driver Code Ends

Some_More_Trees/README.md

@@ -13,3 +13,13 @@
   / \ => / \
   3 2 2 3
  The inorder of mirror is 2 1 3
+
+## 2. Longest Consecutive Sequence in a Binary Tree:
+ Given a Binary Tree find the length of the longest path which comprises of connected nodes with consecutive values in increasing order. 
+ Example 1:
+ Input : 
+  1 
+  / \ 
+  2 3 
+ Output: 2
+ Explanation : Longest sequence is 1, 2.