Preorder Traversal Without Using Recursion

Submitted by heartin on Wed, 11/11/2015 - 09:35

Approach

  • In inorder, we print data and then go to left and right subtree.

  • We can use a stack here.

  • Every time we print a node, we will add its right and left children to the stack in order.

  • Since stack is a LIFO data structure, the left will be poped and printed first.

 

Solution

void preorder(TreeNode n)

{

  TreeNode current = n;

  Stack s = new Stack();

  s.push(current);

  while(!s.isEmpty())

  {

    current = s.pop();

    print(current);

    s.push(current.right);

    s.push(current.left);

  }

}

 

Complexity

Complexity will be O(n)

Extra spac will be taken for the Stack.

Quick Notes Finder Tags

Activities (1) advanced java (1) agile (3) App Servers (6) archived notes (2) Arrays (1) Best Practices (12) Best Practices (Design) (3) Best Practices (Java) (7) Best Practices (Java EE) (1) BigData (3) Chars & Encodings (6) coding problems (2) Collections (15) contests (3) Core Java (All) (55) course plan (2) Database (12) Design patterns (8) dev tools (3) downloads (2) eclipse (9) Essentials (1) examples (14) Exception (1) Exceptions (4) Exercise (1) exercises (6) Getting Started (18) Groovy (2) hadoop (4) hibernate (77) hibernate interview questions (6) History (1) Hot book (5) http monitoring (2) Inheritance (4) intellij (1) java 8 notes (4) Java 9 (1) Java Concepts (7) Java Core (9) java ee exercises (1) java ee interview questions (2) Java Elements (16) Java Environment (1) Java Features (4) java interview points (4) java interview questions (4) javajee initiatives (1) javajee thoughts (3) Java Performance (6) Java Programmer 1 (11) Java Programmer 2 (7) Javascript Frameworks (1) Java SE Professional (1) JPA 1 - Module (6) JPA 1 - Modules (1) JSP (1) Legacy Java (1) linked list (3) maven (1) Multithreading (16) NFR (1) No SQL (1) Object Oriented (9) OCPJP (4) OCPWCD (1) OOAD (3) Operators (4) Overloading (2) Overriding (2) Overviews (1) policies (1) programming (1) Quartz Scheduler (1) Quizzes (17) RabbitMQ (1) references (2) restful web service (3) Searching (1) security (10) Servlets (8) Servlets and JSP (31) Site Usage Guidelines (1) Sorting (1) source code management (1) spring (4) spring boot (3) Spring Examples (1) Spring Features (1) spring jpa (1) Stack (1) Streams & IO (3) Strings (11) SW Developer Tools (2) testing (1) troubleshooting (1) user interface (1) vxml (8) web services (1) Web Technologies (1) Web Technology Books (1) youtube (1)