java - 生成累积频率数但从 0 开始

Question

最近有任务，卡在了这里。问题是“等待时间”。它已生成，但以 0 值开始。我只知道如何计算累积频率，但它不是从 0 开始的。我真的需要帮助。提前致谢。 :)~图1是我的任务。 (我必须像这样做表格)

package simplearray;
import java.util.*;
public class SimpleArray {

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);

    int numberOfProcesses;
    System.out.print("Processes: ");
    numberOfProcesses = input.nextInt();

    String[] process = new String[numberOfProcesses];
    int[] CPUburst = new int[numberOfProcesses];
    int[] priority = new int[numberOfProcesses];

    int[] waitingTime = new int[numberOfProcesses];

    for (int i = 0; i < numberOfProcesses; i++) {
        System.out.print("Process>> ");
        process[i] = input.next();

        System.out.print("Enter the CPU Burst>> ");
        CPUburst[i] = input.nextInt();

        System.out.print("Enter the Priority>> ");
        priority[i] = input.nextInt();
    }

    System.out.println(" | Process | CPU Burst | Priority | Waiting Time | ");

    int temp = 0;
    for (int k = 0; k < numberOfProcesses; k++) {

        waitingTime[k] = waitingTime[k] + CPUburst[k];
        temp = waitingTime[k];

        System.out.println(" |    " + process[k] + "    |    " + CPUburst[k] + "      |    " + priority[k] + "     |    " + waitingTime[k] + "        | ");

    }
}

Figure 1

Answer 1

您正在尝试计算 [k] 处的累积等待时间，这是进程 [k-1] 处的等待时间 + 进程 [k-1] 处的 CPU 突发时间，其中 k > 0。

代码如下:

public class SimpleArray {
public static void main(String[] args) {
    Scanner input = new Scanner(System.in);

    int numberOfProcesses;
    System.out.print("Processes: ");
    numberOfProcesses = input.nextInt();

    String[] process = new String[numberOfProcesses];
    int[] CPUburst = new int[numberOfProcesses];
    int[] priority = new int[numberOfProcesses];

    int[] waitingTime = new int[numberOfProcesses];

    for (int i = 0; i < numberOfProcesses; i++) {
        System.out.print("Process>> ");
        process[i] = input.next();

        System.out.print("Enter the CPU Burst>> ");
        CPUburst[i] = input.nextInt();

        System.out.print("Enter the Priority>> ");
        priority[i] = input.nextInt();
    }

    System.out.println(" | Process | CPU Burst | Priority | Waiting Time | ");

    int temp = 0;
    for (int k = 0; k < numberOfProcesses; k++) {

        if (k > 0)
            waitingTime[k] = waitingTime[k-1] + CPUburst[k-1];

        System.out.println(" |    " + process[k] + "    |    " + CPUburst[k] + "      |    " + priority[k] + "     |    " + waitingTime[k] + "        | ");

    }
    double averageWaitTime = 0;
    if (numberOfProcesses > 0)
        averageWaitTime = (double)waitingTime[numberOfProcesses-1] / (numberOfProcesses);
    System.out.println("Average wait time = "+averageWaitTime);
}
}

产生结果:

| Process | CPU Burst | Priority | Waiting Time | 
|    A    |    7      |    3     |    0        | 
|    B    |    2      |    5     |    7        | 
|    C    |    3      |    1     |    9        | 
|    D    |    6      |    4     |    12        | 
|    E    |    4      |    2     |    18        | 
Average wait time = 3.6

编辑:在运行算法之前按 CPU 突发排序

public class SimpleArray {
public static void main(String[] args) {
    Scanner input = new Scanner(System.in);

    int numberOfProcesses;
    System.out.print("Processes: ");
    numberOfProcesses = input.nextInt();

    String[] process = new String[numberOfProcesses];
    int[] CPUburst = new int[numberOfProcesses];
    int[] priority = new int[numberOfProcesses];

    int[] waitingTime = new int[numberOfProcesses];

    for (int i = 0; i < numberOfProcesses; i++) {
        System.out.print("Process>> ");
        process[i] = input.next();

        System.out.print("Enter the CPU Burst>> ");
        CPUburst[i] = input.nextInt();

        System.out.print("Enter the Priority>> ");
        priority[i] = input.nextInt();
    }

    int tempo;
    String s;
    for (int i = 0; i < numberOfProcesses; i++) {
        for (int j = i + 1; j < numberOfProcesses; j++) {
            if (CPUburst[i] > CPUburst[j]) {
                tempo = CPUburst[i];
                CPUburst[i] = CPUburst[j];
                CPUburst[j] = tempo;
                tempo = priority[i];
                priority[i] = priority[j];
                priority[j] = tempo;
                s = process[i];
                process[i] = process[j];
                process[j] = s;
            }
        }
    }

    System.out.println(" | Process | CPU Burst | Priority | Waiting Time | ");

    int temp = 0;
    for (int k = 0; k < numberOfProcesses; k++) {

        if (k > 0)
            waitingTime[k] = waitingTime[k - 1] + CPUburst[k - 1];

        System.out.println(" |    " + process[k] + "    |    " + CPUburst[k] + "      |    " + priority[k]
                + "     |    " + waitingTime[k] + "        | ");

    }
    double averageWaitTime = 0;
    if (numberOfProcesses > 0)
        averageWaitTime = (double) waitingTime[numberOfProcesses - 1] / (numberOfProcesses);
    System.out.println("Average wait time = " + averageWaitTime);
}
}

现在产生:

 | Process | CPU Burst | Priority | Waiting Time | 
 |    B    |    2      |    5     |    0        | 
 |    C    |    3      |    1     |    2        | 
 |    E    |    4      |    2     |    5        | 
 |    D    |    6      |    4     |    9        | 
 |    A    |    7      |    3     |    15        | 
 Average wait time = 3.0

编辑 2:显示如何确保输入正确

    int numberOfProcesses = 0;
    boolean success = true;
    do {
        try {
            System.out.print("Processes: ");
            String s = input.nextLine();
            numberOfProcesses = Integer.parseInt(s);
            success = true;
        } catch (NumberFormatException e) {
            success = false;
            System.out.println("Wrong Input. Please put integer number.");
        }
    } while (!success);