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52 lines
1.2 KiB
52 lines
1.2 KiB
package 第03期.mca_03;
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import java.util.ArrayList;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Queue;
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// 给你二叉树的根节点 root ，返回其节点值的 层序遍历
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// 即逐层地从左到右访问所有节点
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// 测试链接 : https://leetcode.cn/problems/binary-tree-level-order-traversal/
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public class Code02_LevelTraversalBT {
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// 不提交这个类
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public static class TreeNode {
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public int val;
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public TreeNode left;
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public TreeNode right;
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public TreeNode(int v) {
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val = v;
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}
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}
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// 提交以下的方法
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public static List<List<Integer>> levelOrder(TreeNode root) {
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List<List<Integer>> ans = new ArrayList<>();
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if (root != null) {
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Queue<TreeNode> queue = new LinkedList<>();
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queue.add(root);
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while (!queue.isEmpty()) {
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// 当前轮做几次动作
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int size = queue.size();
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// 当前层的链表
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List<Integer> curLevel = new ArrayList<>();
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for (int i = 0; i < size; i++) {
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TreeNode cur = queue.poll();
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if (cur.left != null) {
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queue.add(cur.left);
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}
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if (cur.right != null) {
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queue.add(cur.right);
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}
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curLevel.add(cur.val);
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}
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ans.add(curLevel);
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}
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}
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return ans;
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}
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}
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