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Thread: Convert Expressions to RPN format using tree

  1. #1
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    Default Convert Expressions to RPN format using tree

    I am trying to fix my code it is duplicating the last output twice
    For inputs you must have spaces. I have attached an snippet of the output.
    My code is converting 1 + 1 into an RPN format 1 1 +
    I am grateful for any help provided


    import java.util.ArrayList;
    import java.util.Scanner;
    import java.util.regex.Pattern;
     
    public class ToPostFix {
     
    static 	ArrayList<String> al= new ArrayList<String>();
    static  ArrayList<String> alex= new ArrayList<String>();
    static String value;
    static String exp;
    	public static void main(String[] args) {
    		System.out.println("Enter your inputs");
    		 Scanner in = new Scanner (System.in);
    		String input = in.nextLine();
    		String[] tokens = input.split("\\s");
    		in.close();
    	for (int i=0; i<tokens.length; i++) {
    		validate(tokens[i]);
    	}
    	   for (String x : tokens) {
     
    			al.add(x);
    			}
     
    	    firstcheck();
    	    secondcheck();
    	    thirdcheck();
     
    	   String[] tokens2= alex.get(alex.size()-1).split("\\s");
     
     
    	    TreeNode myTreeNode = new TreeNode(value, null);
    	    myTreeNode.setValue((tokens2[1]));
    		myTreeNode.setLeft(new TreeNode(tokens2[0], myTreeNode));
    		myTreeNode.setRight(new TreeNode(tokens2[2], myTreeNode));
    	    tree(alex,myTreeNode);
    	    ToPostFix.postOrder(myTreeNode);
    	}
     
    	static void firstcheck() {	   
    	   for(int i = 0; i < al.size() - 1; i++) {
    		   if(al.get(i).equals("(")) {
     
    			   String exp;
    			   exp = al.get(i+1) +" "+ al.get(i+2)+" " + al.get(i+3);
    			   alex.add(exp);
    			   al.remove(i);
    			   al.remove(i);
    			   al.remove(i);
    			   al.remove(i);
    			   al.remove(i);
    			   al.add(1,  "exp" + (alex.size()-1));
    		   }
     
    	   }
    		}
    		static void secondcheck() {
    		   //user regex for that
    		   for(int j = 0; j < al.size() - 1; j++) {
    			   if(al.get(j).equals("*") || al.get(j).equals("/") || al.get(j).equals("%")) {
     
    				   String exp;
    				   exp = al.get(j-1) +" "+ al.get(j)+" " + al.get(j+1);
    				   alex.add(exp);
    				   al.remove(j - 1); 
    				   al.remove(j - 1); 
    				   al.remove(j - 1);
    				   al.add(j - 1,  "exp" + (alex.size()-1));
    			   }  
    		   }
    		}
    		static void thirdcheck()
    		{  
     
    			   for(int k = 0; k <= al.size() - 1; k++) {
    				   if(al.get(k).equals("+") || al.get(k).equals("-")) {
     
    					   String exp;
    					   exp = al.get(k-1) +" "+ al.get(k)+" " + al.get(k+1);
    					   alex.add(exp);
    					   al.remove(k - 1); 
    					   al.remove(k - 1);
    					   al.remove(k - 1);
    					   al.add(k-1,  "exp" + (alex.size()-1));
    					   k -= 1;
     
    				   }   
    				   System.out.println(al.size());
    			   }
    		}
     
    		static void tree(ArrayList<String>alex, TreeNode myTreeNode)	{
     
    			if(myTreeNode.getLeft().getValue().substring(0,1).equals("e")) {
     
    			String[] tokens2= alex.get(alex.size()-1).split("\\s");
    			TreeNode newNode = new TreeNode(tokens2[1], myTreeNode);
    			newNode.setLeft(new TreeNode(tokens2[0], newNode));
    			alex.remove(alex.size()-1);
    			newNode.setRight(new TreeNode(tokens2[2],newNode));
    			myTreeNode.setLeft(newNode);
     
    			tree(alex,newNode);
    		}
     
    		if(myTreeNode.getRight().getValue().substring(0,1).equals("e")) {
     
    			String[] tokens2= alex.get(alex.size()-1).split("\\s");
    			TreeNode newNode = new TreeNode(tokens2[1], myTreeNode);
    			newNode.setLeft(new TreeNode(tokens2[0], newNode));
    			alex.remove(alex.size()-1);
    			newNode.setRight(new TreeNode(tokens2[2],newNode));
    			myTreeNode.setRight(newNode);
    			tree(alex,newNode);
    		}
     
     
    		}
    		static void postOrder(TreeNode myTreeNode) {
    		if(myTreeNode != null) {
    			postOrder(myTreeNode.left);
    			postOrder(myTreeNode.right);
     
    			System.out.printf( myTreeNode.value);
    			}
    		}
     
     
    	static boolean validate (String s) {
    		String regex = "[*/+\\-%]|[()]|\\-?[0-9][\\.0-9]*"; // double forward slash is used to escape, example it would think it was going from 0-9
    												//* means 0 or more
    												//. means floating point
    												//-? allows negative numbers 
    												// ? is used as optional
    		//if (false)
    			//return System.out.println("The input is wrong");
     
     
    		return (Pattern.matches(regex, s));
     
    	}
     
    }
    code RPN converter.jpgError RPN Converter.jpg
    Last edited by johndoe123; November 15th, 2018 at 09:23 AM. Reason: Made some changes

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Convert Expressions to RPN format using tree

    Please copy the contents of the command prompt window and paste it here to show what you are asking about.
    Add some comments showing what you want the output to be.

    Please edit your post and wrap your code with code tags:

    [code]
    **YOUR CODE GOES HERE**
    [/code]

    to get highlighting and preserve formatting.
    If you don't understand my answer, don't ignore it, ask a question.

  3. The Following User Says Thank You to Norm For This Useful Post:

    johndoe123 (November 15th, 2018)

  4. #3
    Junior Member
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    Default Re: Convert Expressions to RPN format using tree

    I resolved this issue with the repeated the last integer. Thanks to all who took a look at it.

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