Java数据结构与经典算法——高手必会

1.大O表示法：粗略的量度方法即算法的速度是如何与数据项的个数相关的算法大O表示法表示的运行时间线性查找 O(N)二分查找 O(logN)无序数组的插入 O(1)有序数组的插入 O(N)无序数组的删除 O(N)有序数组的删除 O(N)O(1)是最优秀的,O(logN)良好,O(N)还可以,O(N2)稍差(在冒泡法中见到)2.排序public class JWzw {//插入排序public void insertArray(Integer []in){int tem = 0;int num = 0;int upnum = 0;for (int i = 0; i < in.length; i++) {for (int j = i - 1; j >= 0; j--) {num++;if (in[j+1] < in[j]) {tem = in[j+1];in[j+1] = in[j];in[j] = tem;upnum++;}else{break;}}}for (int i = 0; i < in.length; i++) {System.out.print(in[i]);if(i < in.length - 1){System.out.print(",");}}System.out.println();System.out.println("插入排序循环次数:" + num);System.out.println("移动次数：" + upnum);System.out.print("\n\n\n");}//选择排序public void chooseArray(Integer []in){int tem = 0;int num = 0;int upnum = 0;for(int i = 0;i < in.length;i++){for(int j = i;j < in.length - 1;j++){num++;if(in[j+1] < in[j]){tem = in[j+1];in[j + 1] = in[j];in[j] = tem;upnum++;}}}for (int i = 0; i < in.length; i++) {System.out.print(in[i]);if(i < in.length - 1){System.out.print(",");}}System.out.println();System.out.println("选择排序循环次数:" + num);System.out.println("移动次数：" + upnum);System.out.print("\n\n\n");}//冒泡排序public void efferArray(Integer []in){int tem = 0;int num = 0;int upnum = 0;for(int i = 0;i < in.length;i++){for(int j = i;j < in.length - 1;j++){num++;if(in[j+1] < in[i]){tem = in[j+1];in[j+1] = in[i];in[i] = tem;upnum++;}}}for (int i = 0; i < in.length; i++) {System.out.print(in[i]);if(i < in.length - 1){System.out.print(",");}}System.out.println();System.out.println("冒泡排序循环次数:" + num);System.out.println("移动次数：" + upnum);System.out.print("\n\n\n");}//打印乘法口诀public void printMulti(){for (int j = 1; j < 10; j++) {for (int i = 1; i <= j; i++) {System.out.print(i + " * " + j + " = " + j * i + "\t");}System.out.print("\t\n");}System.out.print("\n\n\n");}//打印N * 1 + N * 2 + N * 3 =num的所有组合public void printNumAssemble(int num){for (int i = 0; i < num + 1; i++) {for (int j = 0; j < num / 2 +1; j++) {for (int in = 0; in < num / 3 + 1; in++) {if (i * 1 + j * 2 + in * 3 == num) {System.out.println("小马" + i + ",\t中马" + j + ",\t大马" + in);}}}}}/*** @param args*/public static void main(String[] args) {JWzw jwzw = new JWzw();int num = 3;jwzw.printMulti();//打印乘法口诀jwzw.printNumAssemble(100);//打印N * 1 + N * 2 + N * 3 =num的所有组合Integer in[] = {8,89,5,84,3,45,12,33,77,98,456,878,654,213,897};jwzw.efferArray(in);//冒泡排序Integer in1[] = {8,89,5,84,3,45,12,33,77,98,456,878,654,213,897};jwzw.insertArray(in1);//插入排序Integer in2[] = {8,89,5,84,3,45,12,33,77,98,456,878,654,213,897};jwzw.chooseArray(in2);//选择排序//int i = num++;//System.out.println(i);System.out.println(1000>>2);}}3.优先级队列class PriorityQueue {private long[] a = null;private int nItems = 0;private int maxSize = 0;public PriorityQueue(int maxSize) {a = new long[maxSize];this.maxSize = maxSize;nItems = 0;}public void insert(long l) {//优先级队列的插入不是队尾,而是选择一个合适的按照某种顺序插入的//当队列长度为0时，如下//不为0时,将所有比要插入的数小的数据后移,这样大的数就在队列的头部了int i = 0;if(nItems == 0) {a[0] = l;} else {for(i=nItems-1; i>=0; i--) {if(l < a[i])a[i+1] = a[i];elsebreak;}a[i+1] = l;}nItems++;}public long remove() {//移出的是数组最上端的数，这样减少数组元素的移动return a[--nItems];}public boolean isEmpty() {return (nItems == 0);}public boolean isFull() {return (nItems == maxSize);}public int size() {return nItems;}}public class duilie {// 队列体类private duilie s;private String data;duilie(String data) {this.data = data;}public String getData() {return data;}public void setData(String data) {this.data = data;}public duilie getS() {return s;}public void setS(duilie s) {this.s = s;}}public class duiliecz {// 队列操作类/*** @param args*/private int i = 0;// 队列长private duilie top = new duilie("");// 队列头private duilie end = new duilie("");// 队列尾public void add(String s) {// 添加队列duilie m = new duilie(s);if (i != 0) {m.setS(top.getS());top.setS(m);} else {top.setS(m);end.setS(m);}i++;}4.队列public void del() {// 删除队尾if (i == 0) {return;} else if (i == 1) {top.setS(null);end.setS(null);} else {duilie top1 = new duilie("");// 队列底查找用缓存 top1.setS(top.getS());while (!top1.getS().getS().equals(end.getS())) { top1.setS(top1.getS().getS());}end.setS(top1.getS());}i--;}public static void main(String[] args) {// TODO Auto-generated method stubduiliecz m = new duiliecz();m.add("1");m.add("2");m.add("3");m.add("4");for (int n = 0; n < 4; n++) {m.del();}}public int getI() {return i;}public duilie getEnd() {return end;}public duilie getTop() {return top;}}5.栈public class Stack {int[] arr;int len = 0;public Stack() {arr = new int[100];}public Stack(int n) {arr = new int[n];}public int size() {return len + 1;}// 扩大数组public void resize() {int[] b = new int[arr.length * 2];System.arraycopy(arr, 0, b, 0, arr.length);arr = b;}public void show() {for (int i = 0; i < len; i++) {System.out.print(arr[i] + " ");}System.out.println();}// 进栈public void push(int a) {if (len >= arr.length)resize();arr[len] = a;len++;}// 出栈public int pop() {if (len == 0) {System.out.println();System.out.println("stack is empty!");return -1;}int a = arr[len - 1];arr[len - 1] = 0;len--;return a;}}6.链表class Node {Object data;Node next;public Node(Object data) {setData(data);}public void setData(Object data) {this.data = data;}public Object getData() {return data;}}class Link {Node head;int size = 0;public void add(Object data) {Node n = new Node(data);if (head == null) {head = n;} else {Node current = head;while (true) {if (current.next == null) {break;}current = current.next;}current.next = n;}size++;}public void show() {Node current = head;if (current != null) {while (true) {System.out.println(current);if (current == null) {break;}current = current.next;}} else {System.out.println("link is empty");}}public Object get(int index) {// ....}public int size() {return size;}}7.单链表class Node // 节点类，单链表上的节点{String data; // 数据域，存放String类的数据Node next; // 指向下一个节点Node(String data) {this.data = data; // 构造函数}String get() {return data; // 返回数据}}class MyLinkList // 链表类{Node first; // 头节点int size; // 链表长度MyLinkList(String arg[]) {// Node first = new Node("head");//生成头节点first = new Node("head"); // J.F. 这里不需要定义局部变量 first// 如果定义了局部变量，那成员变量 first 就一直没有用上// 所以，它一直为空size = 0;Node p = first;for (int i = 0; i < arg.length; i++) // 将arg数组中的元素分别放入链表中{Node q = new Node(arg[i]);q.next = p.next; // 每一个节点存放一个arg数组中的元素p.next = q;p = p.next;size++;}}MyLinkList() // 无参数构造函数{// Node first = new Node("head");first = new Node("head"); // J.F. 这里犯了和上一个构造方法同样的错误size = 0;}int size() // 返回链表长度{return size;}void insert(Node a, int index) // 将节点a 插入链表中的第index个位置{Node temp = first;for (int i = 0; i < index; i++) {temp = temp.next;// 找到插入节点的前一节点}a.next = temp.next; // 插入节点temp.next = a;size++;}Node del(int index) // 删除第index个节点，并返回该值{Node temp = first;for (int i = 0; i < index; i++) {temp = temp.next;// 找到被删除节点的前一节点}Node node = temp.next;temp.next = node.next;size--; // 删除该节点，链表长度减一return node;}void print() // 在屏幕上输出该链表（这段程序总是出错，不知道错在哪里）{Node temp = first;for (int i = 1; i < size; i++) // 将各个节点分别在屏幕上输出{temp = temp.next;System.out.print(temp.get() + "->");}}void reverse() // 倒置该链表{for (int i = 0; i < size; i++) {insert(del(size - 1), 0); // 将最后一个节点插入到最前// J.F. 最后一个节点的 index 应该是 size - 1// 因为第一个节点的 index 是 0}}String get(int index) // 查找第index个节点，返回其值{if (index >= size) {return null;}Node temp = first;for (int i = 0; i < index; i++) {temp = temp.next;// 找到被查找节点的前一节点}return temp.next.get();}}class MyStack // 堆栈类，用单链表实现{MyLinkList tmp;Node temp;MyStack() {// MyLinkList tmp = new MyLinkList();tmp = new MyLinkList(); // J.F. 和 MyLinkList 构造方法同样的错误}void push(String a) // 压栈，即往链表首部插入一个节点{Node temp = new Node(a);tmp.insert(temp, 0);}String pop() // 出栈，将链表第一个节点删除{Node a = tmp.del(0);return a.get();}int size() {return tmp.size();}boolean empty() // 判断堆栈是否为空{if (tmp.size() == 0)return false;elsereturn true;}}public class MyLinkListTest // 测试程序部分{public static void main(String arg[]) // 程序入口{if ((arg.length == 0) || (arg.length > 10))System.out.println("长度超过限制或者缺少参数");else {MyLinkList ll = new MyLinkList(arg); // 创建一个链表ll.print(); // 先输出该链表（运行到这一步抛出异常）ll.reverse(); // 倒置该链表ll.print(); // 再输出倒置后的链表String data[] = new String[10];int i;for (i = 0; i < ll.size(); i++) {data[i] = ll.get(i); // 将链表中的数据放入数组}// sort(data);// 按升序排列data中的数据（有没有现成的排序函数？）for (i = 0; i < ll.size(); i++) {System.out.print(data[i] + ";"); // 输出数组中元素}System.out.println();MyStack s = new MyStack(); // 创建堆栈实例sfor (i = 0; i < ll.size(); i++) {s.push(data[i]); // 将数组元素压栈}while (!s.empty()) {System.out.print(s.pop() + ";"); // 再将堆栈里的元素弹出}}}}8.双端链表class Link {public int iData = 0;public Link next = null;public Link(int iData) {this.iData = iData;}public void display() {System.out.print(iData + " ");}}class FirstLastList {private Link first = null;private Link last = null;public FirstLastList() {first = null;last = null;}public void insertFirst(int key) {Link newLink = new Link(key);if (this.isEmpty())last = newLink;newLink.next = first;first = newLink;}public void insertLast(int key) {Link newLink = new Link(key);if (this.isEmpty())first = newLink;elselast.next = newLink;last = newLink;}public Link deleteFirst() {Link temp = first;if (first.next == null)last = null;first = first.next;return temp;}public boolean isEmpty() {return (first == null);}public void displayList() {System.out.print("List (first-->last): ");Link current = first;while (current != null) {current.display();current = current.next;}System.out.println("");}}class FirstLastListApp {public static void main(String[] args) {// TODO Auto-generated method stubFirstLastList theList = new FirstLastList();theList.insertFirst(22); // insert at fronttheList.insertFirst(44);theList.insertFirst(66);theList.insertLast(11); // insert at reartheList.insertLast(33);theList.insertLast(55);theList.displayList(); // display the listtheList.deleteFirst(); // delete first two itemstheList.deleteFirst();theList.displayList(); // display again }}9.有序链表package arithmetic;class Link {public int iData = 0;public Link next = null;public Link(int iData) {this.iData = iData;}public void display() {System.out.print(iData + " ");}}class SortedList {private Link first = null;public SortedList() {first = null;}public void insert(int key) {Link newLink = new Link(key);Link previous = null;Link current = first;// while的第一个条件是没有到达链表的尾端,第二个是按顺序找到一个合适的位置while (current != null && key > current.iData) {previous = current;current = current.next;}// 如果是空表或者要插入的元素最小,则在表头插入keyif (current == first)first = newLink;elseprevious.next = newLink;newLink.next = current;}/*** 删除表头的节点** @return要删除的节点*/public Link remove() {Link temp = first;first = first.next;return temp;}public boolean isEmpty() {return (first == null);}public void displayList() {System.out.print("List (first-->last): ");Link current = first; // start at beginning of listwhile (current != null) // until end of list,{current.display(); // print datacurrent = current.next; // move to next link}System.out.println("");}}class SortedListApp {public static void main(String[] args) { // create new listSortedList theSortedList = new SortedList();theSortedList.insert(20); // insert 2 itemstheSortedList.insert(40);theSortedList.displayList(); // display listtheSortedList.insert(10); // insert 3 more itemstheSortedList.insert(30);theSortedList.insert(50);theSortedList.displayList(); // display listtheSortedList.remove(); // remove an itemtheSortedList.displayList(); // display list }}10.双向链表class Link {// 双向链表,有两个指针,一个向前,一个向后public int iData = 0;public Link previous = null;public Link next = null;public Link(int iData) {this.iData = iData;}public void display() {System.out.print(iData + " ");}}class DoublyLinked {// 分别指向链表的表头和表尾private Link first = null;private Link last = null;public boolean isEmpty() {return first == null;}/*** 在表头插入数据** @param要插入的节点的数据*/public void insertFirst(int key) {Link newLink = new Link(key);// 如果开始链表为空,则插入第一个数据后,last也指向第一个数据if (this.isEmpty())last = newLink;else {// 表不为空的情况first.previous = newLink;newLink.next = first;}// 无论怎样,插入后都的让first重新指向第一个节点first = newLink;}public void insertLast(int key) {// 在尾端插入数据,同上Link newLink = new Link(key);if (this.isEmpty())first = newLink;else {last.next = newLink;newLink.previous = last;}last = newLink;}/*** 在指定的节点后插入数据** @param key* 指定的节点的值* @param iData* 要插入的数据* @return是否插入成功*/public boolean insertAfter(int key, int iData) {Link newLink = new Link(key);Link current = first;// 从first开始遍历,看能否找到以key为关键字的节点while (current.iData != key) {current = current.next;// 若能找到就跳出循环,否则返回false,插入失败if (current == null)return false;}// 如果插入点在last的位置if (current == last) {last = newLink;} else {// 非last位置,交换各个next和previous的指针newLink.next = current.next;current.next.previous = newLink;}current.next = newLink;newLink.previous = current;return true;}/*** 删除表头的节点** @return*/public Link deleteFirst() {Link temp = first;// 如果表中只有一个元素,删除后则为空表,所以last=nullif (first.next == null)last = null;else// 否则,让第二个元素的previous=nullfirst.next.previous = null;// 删除头指针,则first指向原来的secondfirst = first.next;return temp;}public Link deleteLast() {// 同上Link temp = last;if (last.previous == null)first = null;elselast.previous.next = null;last = last.previous;return temp;}public Link deleteKey(int key) {Link current = first;// 遍历整个链表查找对应的key,如果查到跳出循环,否则...while (current.iData != key) {current = current.next;// ...否则遍历到表尾,说明不存在此key,返回null,删除失败if (current == null)return null;}if (current == first)first = first.next;elsecurrent.previous.next = current.next;if (current == last)last = last.previous;elsecurrent.next.previous = current.previous;return current;}public void displayForward() {Link current = first;while (current != null) {current.display();current = current.next;}System.out.println();}public void displayBackward() {Link current = last;while (current != null) {current.display();current = current.previous;}System.out.println();}}class DoublyLinkedApp {public static void main(String[] args) { // make a new list DoublyLinked theList = new DoublyLinked();theList.insertFirst(22); // insert at fronttheList.insertFirst(44);theList.insertFirst(66);theList.insertLast(11); // insert at reartheList.insertLast(33);theList.insertLast(55);theList.displayForward(); // display list forwardtheList.displayBackward(); // display list backwardtheList.deleteFirst(); // delete first itemtheList.deleteLast(); // delete last itemtheList.deleteKey(11); // delete item with key 11theList.displayForward(); // display list forwardtheList.insertAfter(22, 77); // insert 77 after 22theList.insertAfter(33, 88); // insert 88 after 33theList.displayForward(); // display list forward}}11.实现二叉树前序遍历迭代器class TreeNode 这个类用来声明树的结点，其中有左子树、右子树和自身的内容。