线性结构与非线性结构
线性结构
- 线性结构作为最常用的数据结构,其特点是数据元素之间存在一对一的线性关系
- 线性结构有两种不同的存储结构,即顺序存储结构(数组)和链式存储结构(链表)。顺序存储的线性表称为顺序表,顺序表中的存储元素是连续(地址连续)的
- 链式存储的线性表称为链表,链表中的存储元素不一定是连续的,元素节点中存放数据元素以及相邻元素的地址信息
- 线性结构常见的有:数组、队列、链表和栈
非线性结构
非线性结构包括:二维数组,多维数组,广义表,树结构,图结构
稀疏数组
当一个数组中大部分元素为0,或者为同一个值的数组时,可以使用稀疏数组来保存该数组。
稀疏数组的处理方法是:
- 记录数组一共有几行几列,有多少个不同的值
- 把具有不同值的元素的行列及值记录在一个小规模的数组中,从而缩小程序的规模
二维数组转稀疏数组的思路:
- 遍历原始的二维数组,得到有效数据的个数sum
- 根据sum就可以创建稀疏数组sparseArr int[sum+1][3]
- 将二维数组的有效数据存入到稀疏数组
稀疏数组转原始的二维数组的思路:
- 先读取稀疏数组的第一行,根据第一行的数据创建原始的二维数组,例chessArr2=int[11][11]
- 再读取稀疏数组后几行的数据,并赋给原始的二维数组即可
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| public class SparseArray { public static void main(String[] args) { int[][] chessArr1 = new int[11][11]; chessArr1[1][2] = 1; chessArr1[2][3] = 2; System.out.println("原始的二维数组~~~"); for (int[] row : chessArr1) { for (int data : row) { System.out.printf("%d\t", data); } System.out.println(); } int sum = 0; for (int i = 0; i < chessArr1.length; i++) { for (int j = 0; j < chessArr1.length; j++) { if (chessArr1[i][j] != 0) { sum++; } } } int[][] sparseArr = new int[sum + 1][3]; sparseArr[0][0] = 11; sparseArr[0][1] = 11; sparseArr[0][2] = sum; int count = 0; for (int i = 0; i < chessArr1.length; i++) { for (int j = 0; j < chessArr1.length; j++) { if (chessArr1[i][j] != 0) { count++; sparseArr[count][0] = i; sparseArr[count][1] = j; sparseArr[count][2] = chessArr1[i][j]; } } } System.out.println(); System.out.println("得到的稀疏数组为~~~"); System.out.printf("%s\t%s\t%s\t", "row", "col", "val"); System.out.println(); for (int i = 0; i < sparseArr.length; i++) { System.out.printf("%d\t%d\t%d\t\n", sparseArr[i][0], sparseArr[i][1], sparseArr[i][2]); } int[][] chessArr2 = new int[sparseArr[0][0]][sparseArr[0][1]]; for (int i = 1; i < sparseArr.length; i++) { chessArr2[sparseArr[i][0]][sparseArr[i][1]] = sparseArr[i][2]; } System.out.println(); System.out.println("恢复后的二维数组~~~"); for (int[] row : chessArr2) { for (int data : row) { System.out.printf("%d\t", data); } System.out.println(); } } } import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException;
public class SparseArrayIO { public static void main(String[] args) throws IOException { BufferedReader br = new BufferedReader(new FileReader("D://xiaojia/SparseArr.data")); BufferedWriter bw = new BufferedWriter(new FileWriter("D://xiaojia/SparseArr.data")); BufferedReader br2 = new BufferedReader(new FileReader("D://xiaojia/SparseArr.data")); int[][] chessArr1 = new int[11][11]; chessArr1[1][2] = 1; chessArr1[2][3] = 2; System.out.println("原始的二维数组~~~"); for (int[] row : chessArr1) { for (int data : row) { System.out.printf("%d\t", data); } System.out.println(); } int sum = 0; for (int i = 0; i < chessArr1.length; i++) { for (int j = 0; j < chessArr1.length; j++) { if (chessArr1[i][j] != 0) { sum++; } } } int[][] sparseArr = new int[sum + 1][3]; sparseArr[0][0] = 11; sparseArr[0][1] = 11; sparseArr[0][2] = sum; int count = 0; for (int i = 0; i < chessArr1.length; i++) { for (int j = 0; j < chessArr1.length; j++) { if (chessArr1[i][j] != 0) { count++; sparseArr[count][0] = i; sparseArr[count][1] = j; sparseArr[count][2] = chessArr1[i][j]; } } } for (int i = 0; i < sparseArr.length; i++) { bw.write(sparseArr[i][0] + "\t" + sparseArr[i][1] + "\t" + sparseArr[i][2]); bw.newLine(); bw.flush(); } bw.close(); String str; int row = 0; while ((str = br.readLine()) != null) { row++; } String line; int count2 = 0; int[][] sparseArr2 = new int[row][3]; while ((line = br2.readLine()) != null) { String[] str1 = line.split("\t"); for (int i = 0; i < str1.length; i++) { sparseArr2[count2][i] = Integer.parseInt(str1[i]); } count2++; } int[][] chessArr2 = new int[sparseArr2[0][0]][sparseArr2[0][1]]; for (int i = 1; i < sparseArr2.length; i++) { chessArr2[sparseArr2[i][0]][sparseArr2[i][1]] = sparseArr2[i][2]; } System.out.println(); System.out.println("恢复后的二维数组~~~"); for (int[] r : chessArr2) { for (int data : r) { System.out.print(data + "\t"); } System.out.println(); } } }
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队列
- 队列是一个有序列表,可以用数组或是链表来实现。
- 遵循先入先出的原则
数组模拟队列
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| import java.util.Scanner;
public class ArrayQueueDemo { public static void main(String[] args) { ArrayQueue queue = new ArrayQueue(3); char key = ' '; Scanner sc = new Scanner(System.in); boolean loop = true; while (loop) { System.out.println("s(show):显示队列"); System.out.println("e(exit):退出程序"); System.out.println("a(add):添加数据到队列"); System.out.println("g(get):从队列取出数据"); System.out.println("h(head):查看队列头的数据"); key = sc.next().charAt(0); switch (key) { case 's': queue.showQueue(); break; case 'a': System.out.println("请输入一个数字:"); int value = sc.nextInt(); queue.addQueue(value); break; case 'g': try { int res = queue.getQueue(); System.out.printf("取出的数据是%d\n", res); } catch (Exception e) { System.out.println(e.getMessage()); } break; case 'h': try { int res = queue.headQueue(); System.out.printf("队列头的数据是%d\n", res); } catch (Exception e) { System.out.println(e.getMessage()); } break; case 'e': sc.close(); loop = false; break; default: break; } } System.out.println("程序退出~~~"); } }
class ArrayQueue { private int maxSize; private int front; private int rear; private int[] arr;
public ArrayQueue(int arrMaxSize) { maxSize = arrMaxSize; arr = new int[maxSize]; front = -1; rear = -1; }
public boolean isFull() { return rear == maxSize - 1; }
public boolean isEmpty() { return front == rear; }
public void addQueue(int n) { if (isFull()) { System.out.println("队列满,不能加入数据"); return; } rear++; arr[rear] = n; }
public int getQueue() { if (isEmpty()) { throw new RuntimeException("队列空,不能取数据"); } front++; return arr[front]; }
public void showQueue() { if (isEmpty()) { System.out.println("队列空的,没有数据~~~"); return; } for (int i = 0; i < arr.length; i++) { System.out.printf("arr[%d]=%d\n", i, arr[i]); } }
public int headQueue() { if (isEmpty()) { throw new RuntimeException("队列空的,没有数据~~~"); } return arr[front + 1]; } }
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问题分析并优化:
- 目前数组使用一次就不能用了,没有达到复用的效果
- 将这个数组使用算法,改进成一个环形的队列 取模%方式
数组模拟环形队列
思路分析:
- front变量的含义做一个调整:front指向队列的第一个元素,也就是说arr[front]就是队列的第一个元素,front初始值为0
- rear变量的含义做一个调整:rear指向队列的最后一个元素的后一个位置,因为希望空出一个空间作为一个约定,rear初始值为0
- 当队列满的条件,(rear+1)%maxSize==front【满】
- 当队列空的条件,rear==front【空】
- 队列中有效的数据的个数(rear+maxSize-front)%maxSize
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| import java.util.Scanner;
public class CircleQueueDemo { public static void main(String[] args) { CircleArray queue = new CircleArray(3); char key = ' '; Scanner sc = new Scanner(System.in); boolean loop = true; while (loop) { System.out.println("s(show):显示队列"); System.out.println("e(exit):退出程序"); System.out.println("a(add):添加数据到队列"); System.out.println("g(get):从队列取出数据"); System.out.println("h(head):查看队列头的数据"); key = sc.next().charAt(0); switch (key) { case 's': queue.showQueue(); break; case 'a': System.out.println("请输入一个数字:"); int value = sc.nextInt(); queue.addQueue(value); break; case 'g': try { int res = queue.getQueue(); System.out.printf("取出的数据是%d\n", res); } catch (Exception e) { System.out.println(e.getMessage()); } break; case 'h': try { int res = queue.headQueue(); System.out.printf("队列头的数据是%d\n", res); } catch (Exception e) { System.out.println(e.getMessage()); } break; case 'e': sc.close(); loop = false; break; default: break; } } System.out.println("程序退出~~~"); } }
class CircleArray { private int maxSize;
private int front;
private int rear; private int[] arr;
public CircleArray(int arrMaxSize) { maxSize = arrMaxSize; arr = new int[maxSize]; }
public boolean isFull() { return (rear + 1) % maxSize == front; }
public boolean isEmpty() { return front == rear; }
public void addQueue(int n) { if (isFull()) { System.out.println("队列满,不能加入数据"); return; } arr[rear] = n; rear = (rear + 1) % maxSize; }
public int getQueue() { if (isEmpty()) { throw new RuntimeException("队列空,不能取数据"); } int value = arr[front]; front = (front + 1) % maxSize; return value; }
public void showQueue() { if (isEmpty()) { System.out.println("队列空的,没有数据~~~"); return; } for (int i = front; i < front + size(); i++) { System.out.printf("arr[%d]=%d\n", i % maxSize, arr[i % maxSize]); } }
public int size() { return (rear + maxSize - front) % maxSize; }
public int headQueue() { if (isEmpty()) { throw new RuntimeException("队列空的,没有数据~~~"); } return arr[front]; } }
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