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Create Preorder Traversal .java

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	`1`	`+/*`
	`2`	`+Given a binary tree, return the preorder traversal of its nodes’ values.`
	`3`	`+`
	`4`	`+Example :`
	`5`	`+Given binary tree`
	`6`	`+`
	`7`	`+ 1`
	`8`	`+ \`
	`9`	`+ 2`
	`10`	`+ /`
	`11`	`+ 3`
	`12`	`+return [1,2,3].`
	`13`	`+`
	`14`	`+Using recursion is not allowed.`
	`15`	`+*/`
	`16`	`+`
	`17`	`+/**`
	`18`	`+ * Definition for binary tree`
	`19`	`+ * class TreeNode {`
	`20`	`+ * int val;`
	`21`	`+ * TreeNode left;`
	`22`	`+ * TreeNode right;`
	`23`	`+ * TreeNode(int x) {`
	`24`	`+ * val = x;`
	`25`	`+ * left=null;`
	`26`	`+ * right=null;`
	`27`	`+ * }`
	`28`	`+ * }`
	`29`	`+ */`
	`30`	`+public class Solution {`
	`31`	`+ public ArrayList<Integer> preorderTraversal(TreeNode A) {`
	`32`	`+ ArrayList<Integer> result = new ArrayList<Integer>();`
	`33`	`+ if(A == null)`
	`34`	`+ return result;`
	`35`	`+ Stack<TreeNode> stk = new Stack<TreeNode>();`
	`36`	`+ stk.push(A);`
	`37`	`+ while(!stk.isEmpty())`
	`38`	`+ {`
	`39`	`+ TreeNode temp = stk.pop();`
	`40`	`+ result.add(temp.val);`
	`41`	`+ if(temp.right != null)`
	`42`	`+ stk.push(temp.right);`
	`43`	`+ if(temp.left != null)`
	`44`	`+ stk.push(temp.left);`
	`45`	`+ }`
	`46`	`+ return result;`
	`47`	`+ }`
	`48`	`+}`

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