From d6f22d3f0417818e6972cce14a7272b9005c1512 Mon Sep 17 00:00:00 2001 From: msb_16686 <636909e3> Date: Thu, 17 Nov 2022 08:45:40 +0800 Subject: [PATCH] =?UTF-8?q?=E7=AE=97=E6=B3=95=EF=BC=9A=E6=89=8B=E5=86=99?= =?UTF-8?q?=E5=A0=86?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- Algorithm/pom.xml | 4 + .../src/main/java/algorithm/C02_Stack.java | 45 +++++++ .../src/main/java/algorithm/C21_Node.java | 62 +++++++++ Algorithm/src/main/java/common/Node.java | 10 ++ Algorithm/src/main/java/common/Student.java | 41 ++++++ .../src/main/java/heap/C01_Comparator.java | 47 +++++++ Algorithm/src/main/java/heap/C02_heap.java | 7 ++ Algorithm/src/main/java/heap/HeapGreater.java | 119 ++++++++++++++++++ 8 files changed, 335 insertions(+) create mode 100644 Algorithm/src/main/java/algorithm/C02_Stack.java create mode 100644 Algorithm/src/main/java/algorithm/C21_Node.java create mode 100644 Algorithm/src/main/java/common/Node.java create mode 100644 Algorithm/src/main/java/common/Student.java create mode 100644 Algorithm/src/main/java/heap/C01_Comparator.java create mode 100644 Algorithm/src/main/java/heap/C02_heap.java create mode 100644 Algorithm/src/main/java/heap/HeapGreater.java diff --git a/Algorithm/pom.xml b/Algorithm/pom.xml index 49e18b2..ddbc6c5 100644 --- a/Algorithm/pom.xml +++ b/Algorithm/pom.xml @@ -7,6 +7,10 @@ org.example Algorithm 1.0-SNAPSHOT + + 17 + 17 + \ No newline at end of file diff --git a/Algorithm/src/main/java/algorithm/C02_Stack.java b/Algorithm/src/main/java/algorithm/C02_Stack.java new file mode 100644 index 0000000..ac9dcc9 --- /dev/null +++ b/Algorithm/src/main/java/algorithm/C02_Stack.java @@ -0,0 +1,45 @@ +package algorithm; + +import java.util.Stack; + +public class C02_Stack { + + /** + * 设计一个特殊的栈，实现基本功能和返回栈最小元素 + * pop、push、getMin操作时间复杂度都为O(1) + *

+ * 两个栈来实现：一个数据栈，一个最小值栈 + * 压入数据栈时，比较当前值和最小栈的栈顶，将小的值压入栈顶 + */ + + public static class MyStack1 { + private Stack dataStack; + private Stack minStack; + + public MyStack1() { + dataStack = new Stack<>(); + minStack = new Stack<>(); + } + + public int push(int e) { + dataStack.push(e); + Integer peek = minStack.peek(); + if (peek == null) { + minStack.push(e); + } else { + minStack.push(Math.min(e, peek)); + } + return e; + } + + public int pop() { + Integer res = dataStack.pop(); + Integer min = minStack.pop(); + return res; + } + + public int getMin() { + return minStack.peek(); + } + } +} diff --git a/Algorithm/src/main/java/algorithm/C21_Node.java b/Algorithm/src/main/java/algorithm/C21_Node.java new file mode 100644 index 0000000..c8ef9e7 --- /dev/null +++ b/Algorithm/src/main/java/algorithm/C21_Node.java @@ -0,0 +1,62 @@ +package algorithm; + +import common.Node; + +public class C21_Node { + + public static void main(String args[]) { + System.out.println("开始："); + for (int i = 0; i < 20; i++) { + Node head = createRandomNode(8, 6); + printNodes(head); + System.out.print(" ===>> "); + Node node = removeValue(head, 5); + printNodes(node); + System.out.println(); + } + } + + public static void printNodes(Node head) { + Node pre = head; + while (pre != null) { + System.out.print(pre.value + " "); + pre = pre.next; + } + } + + public static Node createRandomNode(int len, int max) { + Node head = new Node(randomNum(max)); + Node next = head; + for (int i = 1; i < len; i++) { + int n = randomNum(max); + next.next = new Node(n); + next = next.next; + } + return head; + } + + // 生成一个 [0, n) 的随机数 + public static int randomNum(int n) { + return (int) (Math.random() * n); + } + + public static Node removeValue(Node head, int num) { + while (head != null) { + if (head.value != num) { + break; + } + head = head.next; + } + Node pre = head; + Node cur = head; + while (cur != null) { + if (cur.value == num) { + pre.next = cur.next; + } else { + pre = cur; + } + cur = cur.next; + } + return head; + } +} diff --git a/Algorithm/src/main/java/common/Node.java b/Algorithm/src/main/java/common/Node.java new file mode 100644 index 0000000..18186fc --- /dev/null +++ b/Algorithm/src/main/java/common/Node.java @@ -0,0 +1,10 @@ +package common; + +public class Node { + public int value; + public Node next; + + public Node(int value) { + this.value = value; + } +} diff --git a/Algorithm/src/main/java/common/Student.java b/Algorithm/src/main/java/common/Student.java new file mode 100644 index 0000000..8e0a4ae --- /dev/null +++ b/Algorithm/src/main/java/common/Student.java @@ -0,0 +1,41 @@ +package common; + +public class Student { + + private int id; + private int age; + private String name; + + public Student() { + } + + public Student(int id, int age, String name) { + this.id = id; + this.age = age; + this.name = name; + } + + public int getId() { + return id; + } + + public void setId(int id) { + this.id = id; + } + + public int getAge() { + return age; + } + + public void setAge(int age) { + this.age = age; + } + + public String getName() { + return name; + } + + public void setName(String name) { + this.name = name; + } +} diff --git a/Algorithm/src/main/java/heap/C01_Comparator.java b/Algorithm/src/main/java/heap/C01_Comparator.java new file mode 100644 index 0000000..a7f63ab --- /dev/null +++ b/Algorithm/src/main/java/heap/C01_Comparator.java @@ -0,0 +1,47 @@ +package heap; + + +import common.Student; + +import java.util.Arrays; +import java.util.Comparator; + +public class C01_Comparator { + + public static class Student { + + public int id; + public int age; + public String name; + + public Student(int id, int age, String name) { + this.id = id; + this.age = age; + this.name = name; + } + } + + /** + * 比较器代码 + */ + public static class OrderAsc implements Comparator { + + @Override + public int compare(Student o1, Student o2) { + return o1.id == o2.id ? o1.age - o2.age : o1.id - o2.id; + } + } + + public static void main(String[] args) { + Student s1 = new Student(1, 21, "A"); + Student s2 = new Student(2, 30, "B"); + Student s3 = new Student(3, 21, "C"); + + Student[] s = new Student[]{s1, s2, s3}; + Arrays.sort(s, new OrderAsc()); + System.out.println("====1===="); + for (Student c : s) { + System.out.println("name: " + c.name + ", id: " + c.id + ", age: " + c.age); + } + } +} diff --git a/Algorithm/src/main/java/heap/C02_heap.java b/Algorithm/src/main/java/heap/C02_heap.java new file mode 100644 index 0000000..b1e81a6 --- /dev/null +++ b/Algorithm/src/main/java/heap/C02_heap.java @@ -0,0 +1,7 @@ +package heap; + + +public class C02_heap { + + +} diff --git a/Algorithm/src/main/java/heap/HeapGreater.java b/Algorithm/src/main/java/heap/HeapGreater.java new file mode 100644 index 0000000..9ef8bdd --- /dev/null +++ b/Algorithm/src/main/java/heap/HeapGreater.java @@ -0,0 +1,119 @@ +package heap; + +import java.util.ArrayList; +import java.util.Comparator; +import java.util.HashMap; + +/** + * 手写加强堆 + * + * @param + */ +public class HeapGreater { + + private ArrayList heap; + // 反向索引表 + private HashMap indexMap; + private int heapSize; + private Comparator comp; + + public HeapGreater(Comparator comp) { + heap = new ArrayList<>(); + indexMap = new HashMap<>(); + heapSize = 0; + this.comp = comp; + } + + public boolean isEmpty() { + return heapSize == 0; + } + + public int size() { + return heapSize; + } + + public boolean contains(T obj) { + return indexMap.containsKey(obj); + } + + public T peek() { + return heap.get(0); + } + + public void push(T obj) { + heap.add(obj); + indexMap.put(obj, heapSize); + heapInsert(heapSize++); + } + + public T pop() { + T ans = heap.get(0); + swap(0, heapSize - 1); + indexMap.remove(ans); + heap.remove(--heapSize); + heapify(0); + return ans; + } + + /** + * 修改对象属性后堆重排 + * + * @param obj + */ + public void resign(T obj) { + heapInsert(indexMap.get(obj)); + heapify(indexMap.get(obj)); + } + + /** + * 删除堆任意节点（加强堆特有方法，交换至最后位置删除，原有位置重排） + * + * @param obj + */ + public void remove(T obj) { + T replace = heap.get(heapSize - 1); + int index = indexMap.get(obj); + indexMap.remove(obj); + heap.remove(--heapSize); + if (obj != replace) { + heap.set(index, replace); + indexMap.put(replace, index); + resign(replace); + } + } + + private void heapify(int index) { + int left = index << 1 + 1; + while (left < heapSize) { + int best = left + 1 < heapSize && comp.compare(heap.get(left + 1), heap.get(left)) < 0 ? (left + 1) : left; + best = comp.compare(heap.get(best), heap.get(index)) < 0 ? best : index; + if (best == index) { + break; + } + swap(best, index); + index = best; + left = index << 1 + 1; + } + } + + + private void heapInsert(int index) { + while (comp.compare(heap.get(index), heap.get((index - 1) / 2)) < 0) { + swap(index, (index - 1) / 2); + index = (index - 1) / 2; + } + } + + private void swap(int i, int j) { + T o1 = heap.get(i); + T o2 = heap.get(j); + heap.set(i, o2); + heap.set(j, o1); + indexMap.put(o1, j); + indexMap.put(o2, i); + } + + public static void main(String[] args) { + System.out.println(-1 / 2); + } +}