Commit 926008c

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adding java iteraion

新增java統一迭代法

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Original file line number	Diff line number	Diff line change
`@@ -177,6 +177,8 @@ public:`
`177`	`177`
`178`	`178`
`179`	`179`	`## Java`
	`180`	`+递归`
	`181`	`+`
`180`	`182`	```Java
`181`	`183`	`class Solution {`
`182`	`184`	`int sum;`
`@@ -198,6 +200,42 @@ class Solution {`
`198`	`200`	`}`
`199`	`201`	`}`
`200`	`202`	```
	`203`	`+迭代`
	`204`	`+`
	`205`	+```Java
	`206`	`+class Solution {`
	`207`	`+ //DFS iteraion統一迭代法`
	`208`	`+ public TreeNode convertBST(TreeNode root) {`
	`209`	`+ int pre = 0;`
	`210`	`+ Stack<TreeNode> stack = new Stack<>();`
	`211`	`+ if(root == null) //edge case check`
	`212`	`+ return null;`
	`213`	`+`
	`214`	`+ stack.add(root);`
	`215`	`+`
	`216`	`+ while(!stack.isEmpty()){`
	`217`	`+ TreeNode curr = stack.peek();`
	`218`	`+ //curr != null的狀況,只負責存node到stack中`
	`219`	`+ if(curr != null){`
	`220`	`+ stack.pop();`
	`221`	`+ if(curr.left != null) //左`
	`222`	`+ stack.add(curr.left);`
	`223`	`+ stack.add(curr); //中`
	`224`	`+ stack.add(null);`
	`225`	`+ if(curr.right != null) //右`
	`226`	`+ stack.add(curr.right);`
	`227`	`+ }else{`
	`228`	`+ //curr == null的狀況,只負責做單層邏輯`
	`229`	`+ stack.pop();`
	`230`	`+ TreeNode temp = stack.pop();`
	`231`	`+ temp.val += pre;`
	`232`	`+ pre = temp.val;`
	`233`	`+ }`
	`234`	`+ }`
	`235`	`+ return root;`
	`236`	`+ }`
	`237`	`+}`
	`238`	+```
`201`	`239`
`202`	`240`	`## Python`
`203`	`241`	`递归`

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