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92 lines
2.2 KiB
92 lines
2.2 KiB
package 第02期.mca_01;
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import java.util.LinkedList;
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// 测试链接 : https://leetcode.com/problems/check-completeness-of-a-binary-tree/
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public class Code03_IsCBT {
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// 不要提交这个类
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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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public static boolean isCompleteTree1(TreeNode head) {
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if (head == null) {
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return true;
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}
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LinkedList<TreeNode> queue = new LinkedList<>();
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// 是否遇到过左右两个孩子不双全的节点
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boolean leaf = false;
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TreeNode l = null;
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TreeNode r = null;
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queue.add(head);
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while (!queue.isEmpty()) {
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head = queue.poll();
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l = head.left;
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r = head.right;
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if (
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// 如果遇到了不双全的节点之后，又发现当前节点不是叶节点
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(leaf && (l != null || r != null)) || (l == null && r != null)
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) {
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return false;
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}
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if (l != null) {
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queue.add(l);
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}
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if (r != null) {
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queue.add(r);
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}
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if (l == null || r == null) {
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leaf = true;
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}
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}
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return true;
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}
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public static boolean isCompleteTree2(TreeNode head) {
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return process(head).isCBT;
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}
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public static class Info {
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public boolean isFull;
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public boolean isCBT;
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public int height;
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public Info(boolean full, boolean cbt, int h) {
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isFull = full;
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isCBT = cbt;
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height = h;
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}
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}
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public static Info process(TreeNode x) {
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if (x == null) {
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return new Info(true, true, 0);
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}
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Info leftInfo = process(x.left);
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Info rightInfo = process(x.right);
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int height = Math.max(leftInfo.height, rightInfo.height) + 1;
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boolean isFull = leftInfo.isFull && rightInfo.isFull && leftInfo.height == rightInfo.height;
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boolean isCBT = false;
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if (leftInfo.isFull && rightInfo.isFull && leftInfo.height == rightInfo.height) {
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isCBT = true;
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} else if (leftInfo.isCBT && rightInfo.isFull && leftInfo.height == rightInfo.height + 1) {
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isCBT = true;
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} else if (leftInfo.isFull && rightInfo.isFull && leftInfo.height == rightInfo.height + 1) {
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isCBT = true;
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} else if (leftInfo.isFull && rightInfo.isCBT && leftInfo.height == rightInfo.height) {
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isCBT = true;
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}
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return new Info(isFull, isCBT, height);
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}
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}
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