Commit 68d5bbc

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add q103

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Original file line number	Diff line number	Diff line change
`@@ -119,6 +119,7 @@`
`119`	`119`
`120`	`120`	`- [q94_二叉树的中序遍历](/src/树的遍历/q94_二叉树的中序遍历)`
`121`	`121`	`- [q102_二叉树的层次遍历](/src/树的遍历/q102_二叉树的层次遍历)`
	`122`	`+- [q103_二叉树的锯齿形层序遍历](/src/树的遍历/q103_二叉树的锯齿形层序遍历)`
`122`	`123`	`- [q110_平衡二叉树](/src/树的遍历/q110_平衡二叉树)`
`123`	`124`	`- [q144_二叉树的前序遍历](/src/树的遍历/q144_二叉树的前序遍历)`
`124`	`125`	`- [q145_二叉树的后序遍历](/src/树的遍历/q145_二叉树的后序遍历)`

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Original file line number	Diff line number	Diff line change
`@@ -119,6 +119,7 @@`
`119`	`119`
`120`	`120`	`- [Question 94 : Binary Tree Inorder Traversal](/src/树的遍历/q94_二叉树的中序遍历)`
`121`	`121`	`- [Question 102 : Binary Tree Level Order Traversal](/src/树的遍历/q102_二叉树的层次遍历)`
	`122`	`+- [Question 103 : Binary Tree Zigzag Level Order Traversal](/src/树的遍历/q103_二叉树的锯齿形层序遍历)`
`122`	`123`	`- [Question 110 : Balanced Binary Tree](/src/树的遍历/q110_平衡二叉树)`
`123`	`124`	`- [Question 144 : Binary Tree Preorder Traversal](/src/树的遍历/q144_二叉树的前序遍历)`
`124`	`125`	`- [Question 145 : Binary Tree Postorder Traversal](/src/树的遍历/q145_二叉树的后序遍历)`

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	`1`	`+package 树的遍历.q103_二叉树的锯齿形层序遍历;`
	`2`	`+`
	`3`	`+import java.util.ArrayList;`
	`4`	`+import java.util.LinkedList;`
	`5`	`+import java.util.List;`
	`6`	`+import java.util.Queue;`
	`7`	`+`
	`8`	`+/**`
	`9`	`+ * 和层序遍历相同,额外加一个标记控制插入队列的位置`
	`10`	`+ */`
	`11`	`+public class Solution {`
	`12`	`+`
	`13`	`+ public List<List<Integer>> zigzagLevelOrder(TreeNode root) {`
	`14`	`+ List<List<Integer>> ans = new ArrayList<>();`
	`15`	`+ if (root == null) {`
	`16`	`+ return ans;`
	`17`	`+ }`
	`18`	`+ Queue<TreeNode> queue = new LinkedList<>();`
	`19`	`+ queue.add(root);`
	`20`	`+ boolean flag = true;`
	`21`	`+ while (!queue.isEmpty()) {`
	`22`	`+ List<Integer> list = new ArrayList<>();`
	`23`	`+ int size = queue.size();`
	`24`	`+ while (size > 0) {`
	`25`	`+ TreeNode tn = queue.poll();`
	`26`	`+ if (flag) {`
	`27`	`+ list.add(tn.val);`
	`28`	`+ } else {`
	`29`	`+ list.add(0, tn.val);`
	`30`	`+ }`
	`31`	`+ if (tn.left != null) {`
	`32`	`+ queue.add(tn.left);`
	`33`	`+ }`
	`34`	`+ if (tn.right != null) {`
	`35`	`+ queue.add(tn.right);`
	`36`	`+ }`
	`37`	`+ size--;`
	`38`	`+ }`
	`39`	`+ flag = !flag;`
	`40`	`+ ans.add(list);`
	`41`	`+ }`
	`42`	`+ return ans;`
	`43`	`+ }`
	`44`	`+}`

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