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package class05;
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// 如果一个节点X，它左树结构和右树结构完全一样，那么我们说以X为头的子树是相等子树
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// 给定一棵二叉树的头节点head，返回head整棵树上有多少棵相等子树
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public class Code02_LeftRightSameTreeNumber {
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public static class Node {
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public int value;
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public Node left;
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public Node right;
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public Node(int v) {
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value = v;
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}
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}
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// 时间复杂度O(N * logN)
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public static int sameNumber1(Node head) {
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if (head == null) {
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return 0;
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}
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return sameNumber1(head.left) + sameNumber1(head.right) + (same(head.left, head.right) ? 1 : 0);
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}
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public static boolean same(Node h1, Node h2) {
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if (h1 == null ^ h2 == null) {
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return false;
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}
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if (h1 == null && h2 == null) {
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return true;
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}
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// 两个都不为空
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return h1.value == h2.value && same(h1.left, h2.left) && same(h1.right, h2.right);
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}
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// 时间复杂度O(N)
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public static int sameNumber2(Node head) {
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String algorithm = "SHA-256";
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Hash hash = new Hash(algorithm);
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return process(head, hash).ans;
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}
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public static class Info {
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public int ans;
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public String str;
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public Info(int a, String s) {
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ans = a;
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str = s;
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}
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}
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public static Info process(Node head, Hash hash) {
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if (head == null) {
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return new Info(0, hash.hashCode("#,"));
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}
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Info l = process(head.left, hash);
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Info r = process(head.right, hash);
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int ans = (l.str.equals(r.str) ? 1 : 0) + l.ans + r.ans;
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String str = hash.hashCode(String.valueOf(head.value) + "," + l.str + r.str);
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return new Info(ans, str);
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}
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public static Node randomBinaryTree(int restLevel, int maxValue) {
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if (restLevel == 0) {
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return null;
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}
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Node head = Math.random() < 0.2 ? null : new Node((int) (Math.random() * maxValue));
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if (head != null) {
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head.left = randomBinaryTree(restLevel - 1, maxValue);
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head.right = randomBinaryTree(restLevel - 1, maxValue);
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}
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return head;
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}
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public static void main(String[] args) {
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int maxLevel = 8;
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int maxValue = 4;
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int testTime = 100000;
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System.out.println("测试开始");
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for (int i = 0; i < testTime; i++) {
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Node head = randomBinaryTree(maxLevel, maxValue);
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int ans1 = sameNumber1(head);
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int ans2 = sameNumber2(head);
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if (ans1 != ans2) {
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System.out.println("出错了！");
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System.out.println(ans1);
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System.out.println(ans2);
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}
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}
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System.out.println("测试结束");
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}
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}
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