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Create 107-Binary-Tree-Level-Order-Traversal-II.java

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	`1`	`+//Same just reverse in the end.`
	`2`	`+//Reversing in the end is better than using add(0, E) in case of arraylist as it's an O(1) operation.`
	`3`	`+classSolution {`
	`4`	`+publicList<List<Integer>>levelOrderBottom(TreeNoderoot) {`
	`5`	`+List<List<Integer>>ans =newArrayList<>();`
	`6`	`+if (root ==null)returnans;`
	`7`	`+Queue<TreeNode>q =newLinkedList<>();`
	`8`	`+q.offer(root);`
	`9`	`+while (!q.isEmpty()) {`
	`10`	`+List<Integer>level =newArrayList<>();`
	`11`	`+intsize =q.size();`
	`12`	`+for (inti =0;i<size;i++) {`
	`13`	`+TreeNodecur =q.poll();`
	`14`	`+level.add(cur.val);`
	`15`	`+if (cur.left!=null)q.offer(cur.left);`
	`16`	`+if (cur.right!=null)q.offer(cur.right);`
	`17`	`+ }`
	`18`	`+ans.add(level);`
	`19`	`+ }`
	`20`	`+inti =0 ,j =ans.size()-1;`
	`21`	`+//reverse the list`
	`22`	`+while (i<j) {`
	`23`	`+List<Integer>cur =ans.get(i);`
	`24`	`+ans.set(i,ans.get(j));`
	`25`	`+ans.set(j,cur);`
	`26`	`+i++;`
	`27`	`+j--;`
	`28`	`+ }`
	`29`	`+returnans;`
	`30`	`+ }`
	`31`	`+}`

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