Is Node Present?

Easy

0/40

Average time to solve is 10m

Contributed by

21 upvotes

Asked in companies

Problem statement

For a given Binary Tree of type integer and a number X, find whether a node exists in the tree with data X or not.

Detailed explanation ( Input/output format, Notes, Images )

Input Format:

The first line of each test case contains elements of the first tree in the level order form. The line consists of values of nodes separated by a single space. In case a node is null, we take -1 in its place.

The second line of each test case contains the node value you have to find.

Example

The sequence will be put together in a single line separated by a single space. Hence, for the above-depicted tree, the input will be given as:

1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1

Explanation:

Level 1:
The root node of the tree is 1

Level 2:
Left child of 1 = 2
Right child of 1 = 3

Level 3:
Left child of 2 = 4
Right child of 2 = null (-1)
Left child of 3 = 5
Right child of 3 = 6

Level 4:
Left child of 4 = null (-1)
Right child of 4 = 7
Left child of 5 = null (-1)
Right child of 5 = null (-1)
Left child of 6 = null (-1)
Right child of 6 = null (-1)

Level 5:
Left child of 7 = null (-1)
Right child of 7 = null (-1)

The first not-null node(of the previous level) is treated as the parent of the first two nodes of the current level. The second not-null node (of the previous level) is treated as the parent node for the next two nodes of the current level and so on.
The input ends when all nodes at the last level are null(-1).

Output Format:

The only line of output prints 'true' or 'false'.

The output of each test case should be printed in a separate line.

Note:

You are not required to print anything explicitly. It has already been taken care of.

Constraints:

1 <= N <= 10^5

Where N is the total number of nodes in the binary tree.

Time Limit: 1 sec.

Sample Input 1:

8 3 10 1 6 -1 14 -1 -1 4 7 13 -1 -1 -1 -1 -1 -1 -1
7

Sample Output 1:

true

Explanation For Output 1:

Clearly, we can see that 7 is present in the tree. So, the output will be true.

Sample Input 2:

2 3 4 -1 -1 -1 -1
10

Sample Output 2:

false

Hint 1

How can you check every node in a tree? Can recursion help?

Approaches (1)

Approach 1

Binary Tree Traversals

Use any of the tree traversals in-order, preorder, postorder to traverse the tree. While traversing the tree, check if the current node matches with the given node. Return "true" if any node matches with the given node and stop traversing further and if the tree is completely traversed and none of the nodes match with the given node, then return "false".

You can also use level order traversal for this problem.

Time Complexity

O(N), where ‘N’ is the number of nodes.

In the worst case, we have to visit all the nodes of the tree, so the time complexity will be O(N).