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二叉树套路解法

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xiaotiancai893661742 3 years ago
parent fca8239636
commit c9008b25e8
3 changed files with 393 additions and 106 deletions
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366
src/test/java/zuolaos/jichuban/Code09_二叉树.java
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@ -3,40 +3,285 @@ package zuolaos.jichuban;
import java.util.*; import java.util.*;
public class Code09_二叉树 {
private static class Node { class Node {
Node left; Node left;
Node right; Node right;
int value; int value;
public Node(int value) { public Node(int value) {
this.value = value; this.value = value;
}
}
class 搜索二叉树判断 {
private class Info {
int max;
int min;
boolean isBST;
public Info(int max, int min, boolean isBST) {
this.max = max;
this.min = min;
this.isBST = isBST;
}
public Info process(Node node) {
if (node == null) {
return null;
}
Info leftInfo = process(node.left);
Info rightInfo = process(node.right);
int max = Integer.MIN_VALUE;
int min = Integer.MAX_VALUE;
if (leftInfo != null) {
max = Math.max(max, leftInfo.max);
min = Math.max(min, leftInfo.min);
}
if (rightInfo != null) {
max = Math.max(max, rightInfo.max);
min = Math.max(min, rightInfo.min);
}
boolean isSearch = true;
if (leftInfo != null && (!leftInfo.isBST || leftInfo.max >= node.value)) {
isSearch = false;
}
if (rightInfo != null && (!rightInfo.isBST || rightInfo.min <= node.value)) {
isSearch = false;
}
return new Info(max, min, isSearch);
} }
} }
}
private static class Info { class 平衡二叉树判断 {
private class Info {
int height; int height;
boolean isPing; boolean isBalance;
public Info(int height, boolean isPing) { public Info(int height, boolean isBanlance) {
this.height = height; this.height = height;
this.isPing = isPing; this.isBalance = isBanlance;
} }
} }
private static class Sousuo { public Info process(Node node) {
int max; if (node == null) {
return new Info(0, true);
}
Info leftInfo = process(node.left);
Info rightInfo = process(node.right);
int h = Math.max(leftInfo.height, rightInfo.height) + 1;
boolean isBalance = true;
if (!leftInfo.isBalance
|| !rightInfo.isBalance
|| Math.abs(leftInfo.height - rightInfo.height) > 2) {
isBalance = false;
}
return new Info(h, isBalance);
}
}
class 先序和中序获取树 {
public Node process(int[] pre, int L1, int R1, int[] in, int L2, int R2) {
int root = pre[L1];
Node node = new Node(root);
if (L1 == R1) {
return node;
}
int inIndex = 0;
for (int i = L2; i <= R2; i++) {
if (root == in[i]) {
inIndex = i;
break;
}
}
int lcount = inIndex - L2;
int rcount = R2 - inIndex;
node.left = process(pre, L1 + 1, L1 + lcount, in, L2, inIndex - 1);
node.right = process(pre, R1 - rcount + 1, R1, in, inIndex + 1, R2);
return node;
}
public static void main(String[] args) {
//先
int[] arr1 = {1, 2, 3, 4, 5, 6, 7};
int[] arr2 = {3, 2, 4, 1, 6, 5, 7};
先序和中序获取树 aaa = new 先序和中序获取树();
Node node = aaa.process(arr1, 0, arr1.length - 1, arr2, 0, arr2.length - 1);
System.out.println(node);
}
}
class 节点最大距离 {
private class Info {
int h;
int maxDistance;
public Info(int h, int maxDistance) {
this.h = h;
this.maxDistance = maxDistance;
}
}
public Info process(Node node) {
if (node == null) {
return new Info(0, 0);
}
Info leftInfo = process(node.left);
Info rightInfo = process(node.right);
int h = Math.max(leftInfo.h, rightInfo.h) + 1;
int p1 = leftInfo.h + leftInfo.h + 1;
int p2 = leftInfo.maxDistance;
int p3 = rightInfo.maxDistance;
int maxDistance = Math.max(p1, Math.max(p2, p3));
return new Info(h, maxDistance);
}
}
class 最大的子树是搜索二叉树返回节点 {
}
class 最大的子树是搜索二叉树返回大小 {
private class Info {
int maxBSTSubTreeSize;
int min; int min;
boolean isSousuo; int max;
boolean isBST;
public Sousuo(boolean isSousuo, int max, int min) { public Info(int maxBSTSubTreeSize, int min, int max, boolean isBST) {
this.isSousuo = isSousuo; this.maxBSTSubTreeSize = maxBSTSubTreeSize;
this.max = max;
this.min = min; this.min = min;
this.max = max;
this.isBST = isBST;
}
}
public Info process(Node node) {
if (node == null) {
return null;
}
Info leftInfo = process(node.left);
Info rightInfo = process(node.right);
int max = node.value;
int min = node.value;
if (leftInfo != null) {
max = Math.max(max, leftInfo.max);
min = Math.max(min, leftInfo.min);
}
if (rightInfo != null) {
max = Math.max(max, rightInfo.max);
min = Math.max(min, rightInfo.min);
}
boolean isBST = true;
if (leftInfo != null && (!leftInfo.isBST || leftInfo.max >= node.value)) {
isBST = false;
} }
if (rightInfo != null && (!rightInfo.isBST || rightInfo.min <= node.value)) {
isBST = false;
}
int maxBSTSubTreeSize = 0;
int lMaxBSTSubTreeSize = leftInfo == null ? 0 : leftInfo.maxBSTSubTreeSize;
int rMaxBSTSubTreeSize = rightInfo == null ? 0 : rightInfo.maxBSTSubTreeSize;
if (isBST) {
maxBSTSubTreeSize = lMaxBSTSubTreeSize + rMaxBSTSubTreeSize + 1;
} else {
maxBSTSubTreeSize = Math.max(lMaxBSTSubTreeSize, rMaxBSTSubTreeSize);
}
return new Info(maxBSTSubTreeSize, min, max, isBST);
}
public static void main(String[] args) {
最大的子树是搜索二叉树返回大小 aaa = new 最大的子树是搜索二叉树返回大小();
Node node = new Node(2);
node.left = new Node(1);
node.right = new Node(3);
node.right.right = new Node(1);
Info process = aaa.process(node);
System.out.println(process.maxBSTSubTreeSize);
}
}
class 完全二叉树判断 {
private class Info {
int h;
boolean isFull;
boolean isCo;
public Info(int h, boolean isFull, boolean isCo) {
this.h = h;
this.isFull = isFull;
this.isCo = isCo;
}
}
public Info process(Node node) {
if (node == null) {
return new Info(0, true, true);
}
int h;
boolean isFull;
Info leftInfo = process(node.left);
Info rightInfo = process(node.right);
h = Math.max(leftInfo.h, rightInfo.h) + 1;
isFull = leftInfo.isFull && rightInfo.isFull && leftInfo.h == rightInfo.h;
boolean isCo = false;
if (leftInfo.isFull && rightInfo.isFull && leftInfo.h == rightInfo.h) {
isCo = true;
} else if (leftInfo.isCo && rightInfo.isFull && leftInfo.h == rightInfo.h + 1) {
isCo = true;
} else if (leftInfo.isFull && rightInfo.isFull && leftInfo.h == rightInfo.h + 1) {
isCo = true;
} else if (leftInfo.isFull && rightInfo.isCo && leftInfo.h == rightInfo.h) {
isCo = true;
}
return new Info(h, isFull, isCo);
} }
}
class 满二叉树判断 {
private class Info {
int h;
int nodes;
public Info(int h, int nodes) {
this.h = h;
this.nodes = nodes;
}
}
public Info process(Node node) {
if (node == null) {
return new Info(0, 0);
}
Info leftInfo = process(node.left);
Info rightInfo = process(node.right);
int h = Math.max(leftInfo.h, rightInfo.h) + 1;
int nodes = leftInfo.nodes + rightInfo.nodes + 1;
return new Info(h, nodes);
}
public static void main(String[] args) {
满二叉树判断 aaa = new 满二叉树判断();
Info info = aaa.process(null);
//2的h次方
boolean is = (1 << info.h) - 1 == info.nodes;
}
}
public class Code09_二叉树 {
//前序 中序 后序 //前序 中序 后序
public static void print(Node head) { public static void print(Node head) {
if (head == null) { if (head == null) {
@ -71,59 +316,6 @@ public class Code09_二叉树 {
return heap1.value == heap2.value && isSameTree(heap1.left, heap2.right) && isSameTree(heap2.right, heap2.left); return heap1.value == heap2.value && isSameTree(heap1.left, heap2.right) && isSameTree(heap2.right, heap2.left);
} }
//平衡二叉树的判断
public static Info isPingHengTree(Node x) {
if (x == null) {
return new Info(0, true);
}
Info leftInfo = isPingHengTree(x.left);
//todo 可优化
// if (!leftInfo.isPing) {
// return new Info(0, false);
// }
Info rightInfo = isPingHengTree(x.right);
boolean isping = leftInfo.isPing && rightInfo.isPing && Math.abs(leftInfo.height - rightInfo.height) < 2;
int height = Math.max(leftInfo.height, rightInfo.height) + 1;
return new Info(height, isping);
}
//搜索二叉树的判断
public static Sousuo isSousuoTree(Node x) {
if (x == null) {
return null;
}
Sousuo leftNode = isSousuoTree(x.left);
Sousuo rightNode = isSousuoTree(x.right);
int max = x.value;
int min = x.value;
if (leftNode != null) {
max = Math.max(max, leftNode.max);
min = Math.min(min, leftNode.min);
}
if (rightNode != null) {
max = Math.max(max, rightNode.max);
min = Math.min(min, rightNode.min);
}
boolean isSousuo = true;
if (leftNode != null && !leftNode.isSousuo) {
isSousuo = false;
}
if (leftNode != null && !leftNode.isSousuo) {
isSousuo = false;
}
boolean leftMaxLessX = leftNode == null ? true : leftNode.max < x.value;
boolean rightMinMoreX = rightNode == null ? true : rightNode.min > x.value;
if (!(leftMaxLessX && rightMinMoreX)) {
isSousuo = false;
}
return new Sousuo(isSousuo, max, min);
}
//求最大深度 //求最大深度
public static int maxDepth(Node node) { public static int maxDepth(Node node) {
if (node == null) { if (node == null) {
@ -132,26 +324,6 @@ public class Code09_二叉树 {
return Math.max(maxDepth(node.left), maxDepth(node.right)) + 1; return Math.max(maxDepth(node.left), maxDepth(node.right)) + 1;
} }
//先序数组+中序数组 构造树
public static Node zhongAndXian(int[] pre, int L1, int R1, int[] in, int L2, int R2) {
if (L1 > R1) {
return null;
}
Node head = new Node(pre[L1]);
if (L1 == R1) {
return head;
}
int find = L2;
//todo 可优化
while (in[find] != pre[L1]) {
find++;
}
head.left = zhongAndXian(pre, L1 + 1, L1 + find - L2, in, L2, find - 1);
head.right = zhongAndXian(pre, L1 + find - L2 + 1, R1, in, find + 1, R2);
return head;
}
//按层遍历按序输出 //按层遍历按序输出
public static List<List<Integer>> depthNode(Node node) { public static List<List<Integer>> depthNode(Node node) {
List<List<Integer>> result = new LinkedList<>(); List<List<Integer>> result = new LinkedList<>();
@ -213,19 +385,5 @@ public class Code09_二叉树 {
path.remove(path.size() - 1); path.remove(path.size() - 1);
} }
public static void main(String[] args) {
//先
int[] arr1 = {1, 2, 3, 4, 5, 6, 7};
int[] arr2 = {3, 2, 4, 1, 6, 5, 7};
Node node = zhongAndXian(arr1, 0, arr1.length - 1, arr2, 0, arr2.length - 1);
System.out.println(node);
Node node1 = new Node(1);
node1.left = new Node(2);
node1.left.left = new Node(2);
node1.left.left.left = new Node(2);
node1.right = new Node(2);
System.out.println(isPingHengTree(node1).isPing);
print(node);
}
} }

4
src/test/java/zuolaos/jichuban/Code12_归并排序进阶.java
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@ -6,8 +6,8 @@ public class Code12_归并排序进阶 {
} }
//找到子数组累加和 在lower upper范围内 //找到所有子数组累加和,在[lower upper]范围内的子数组个数
class FindZiShuZuSum { class 子数组累加和在范围内的个数 {
public static int start(int[] arr, int lower, int upper) { public static int start(int[] arr, int lower, int upper) {
int[] help = new int[arr.length]; int[] help = new int[arr.length];
help[0] = arr[0]; help[0] = arr[0];

129
src/test/java/zuolaos/jichuban/Code16_多叉数.java
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@ -0,0 +1,129 @@
package zuolaos.jichuban;
import java.util.ArrayList;
import java.util.List;
public class Code16_多叉数 {
}
class 多叉树序列化和反序列化 {
private class Node {
public int val;
public List<Node> children;
public Node() {
}
public Node(int _val) {
val = _val;
}
public Node(int _val, List<Node> _children) {
val = _val;
children = _children;
}
}
// 提交时不要提交这个类
private class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode(int x) {
val = x;
}
}
//序列化
public TreeNode encode(Node node) {
if (node == null) {
return null;
}
TreeNode treeNode = new TreeNode(node.val);
treeNode.left = en(node.children);
return treeNode;
}
private TreeNode en(List<Node> children) {
TreeNode head = null;
//上一个节点的位置
TreeNode last = null;
for (Node child : children) {
TreeNode treeNode = new TreeNode(child.val);
if (head == null) {
head = treeNode;
} else {
last.right = treeNode;
}
last = treeNode;
last.left = en(child.children);
}
return head;
}
//反序列化
public Node decode(TreeNode treeNode) {
if (treeNode == null) {
return null;
}
Node node = new Node(treeNode.val, de(treeNode));
return node;
}
private List<Node> de(TreeNode root) {
List<Node> nodes = null;
while (root != null) {
if (nodes == null) {
nodes = new ArrayList<>();
}
Node cur = new Node(root.val, de(root.left));
nodes.add(cur);
root = root.right;
}
return nodes;
}
}
class 不能相邻的节点快乐值更多 {
private class Info {
int yes; //当前节点去的快乐值
int no; //当前节点去的快乐值
public Info(int yes, int no) {
this.yes = yes;
this.no = no;
}
}
private class Employee {
public int happy;
public List<Employee> nexts;
public Employee(int h) {
happy = h;
nexts = new ArrayList<>();
}
}
public Info process(Employee employee) {
if (employee == null) {
return new Info(0, 0);
}
int yes = 0; //当前节点去的快乐值
int no = 0; //当前节点去的快乐值
for (Employee next : employee.nexts) {
Info nextInfo = process(next);
yes += nextInfo.no;
no += Math.max(nextInfo.yes, nextInfo.no);
}
return new Info(yes, no);
}
}
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