c语言实现FCFS、SJF、PSA、RR的代码

以下是C语言实现FCFS、SJF、PSA、RR的代码。

FCFS（先来先服务）：

#include<stdio.h>

int main()
{
    int bt[20], wt[20], tat[20], n, i, j;
    float avwt = 0, avtat = 0;

    printf("Enter total number of processes(maximum 20): ");
    scanf("%d", &n);

    printf("\nEnter Process Burst Time: \n");
    for(i = 0; i < n; i++)
    {
        printf("P[%d]: ", i+1);
        scanf("%d", &bt[i]);
    }

    wt[0] = 0;
    for(i = 1; i < n; i++)
    {
        wt[i] = 0;
        for(j = 0; j < i; j++)
            wt[i] += bt[j];
    }

    printf("\nProcess\t\tBurst Time\tWaiting Time\tTurnaround Time");

    for(i = 0; i < n; i++)
    {
        tat[i] = bt[i] + wt[i];
        avwt += wt[i];
        avtat += tat[i];
        printf("\nP[%d]\t\t%d\t\t%d\t\t%d", i+1, bt[i], wt[i], tat[i]);
    }

    avwt /= i;
    avtat /= i;
    printf("\n\nAverage Waiting Time: %f", avwt);
    printf("\nAverage Turnaround Time: %f", avtat);

    return 0;
}

SJF（短作业优先）：

#include<stdio.h>

int main()
{
    int bt[20], wt[20], tat[20], p[20], i, j, n, temp;
    float avwt = 0, avtat = 0;

    printf("Enter total number of processes(maximum 20): ");
    scanf("%d", &n);

    printf("\nEnter Process Burst Time: \n");
    for(i = 0; i < n; i++)
    {
        printf("P[%d]: ", i+1);
        scanf("%d", &bt[i]);
        p[i] = i+1;
    }

    for(i = 0; i < n; i++)
    {
        for(j = i+1; j < n; j++)
        {
            if(bt[i] > bt[j])
            {
                temp = bt[i];
                bt[i] = bt[j];
                bt[j] = temp;

                temp = p[i];
                p[i] = p[j];
                p[j] = temp;
            }
        }
    }

    wt[0] = 0;
    for(i = 1; i < n; i++)
    {
        wt[i] = 0;
        for(j = 0; j < i; j++)
            wt[i] += bt[j];
    }

    printf("\nProcess\t\tBurst Time\tWaiting Time\tTurnaround Time");

    for(i = 0; i < n; i++)
    {
        tat[i] = bt[i] + wt[i];
        avwt += wt[i];
        avtat += tat[i];
        printf("\nP[%d]\t\t%d\t\t%d\t\t%d", p[i], bt[i], wt[i], tat[i]);
    }

    avwt /= i;
    avtat /= i;
    printf("\n\nAverage Waiting Time: %f", avwt);
    printf("\nAverage Turnaround Time: %f", avtat);

    return 0;
}

PSA（优先级调度算法）：

#include<stdio.h>

int main()
{
    int bt[20], wt[20], tat[20], p[20], pr[20], i, j, n, temp;
    float avwt = 0, avtat = 0;

    printf("Enter total number of processes(maximum 20): ");
    scanf("%d", &n);

    printf("\nEnter Process Burst Time and Priority: \n");
    for(i = 0; i < n; i++)
    {
        printf("P[%d]: ", i+1);
        scanf("%d %d", &bt[i], &pr[i]);
        p[i] = i+1;
    }

    for(i = 0; i < n; i++)
    {
        for(j = i+1; j < n; j++)
        {
            if(pr[i] > pr[j])
            {
                temp = bt[i];
                bt[i] = bt[j];
                bt[j] = temp;

                temp = pr[i];
                pr[i] = pr[j];
                pr[j] = temp;

                temp = p[i];
                p[i] = p[j];
                p[j] = temp;
            }
        }
    }

    wt[0] = 0;
    for(i = 1; i < n; i++)
    {
        wt[i] = 0;
        for(j = 0; j < i; j++)
            wt[i] += bt[j];
    }

    printf("\nProcess\t\tBurst Time\tWaiting Time\tTurnaround Time");

    for(i = 0; i < n; i++)
    {
        tat[i] = bt[i] + wt[i];
        avwt += wt[i];
        avtat += tat[i];
        printf("\nP[%d]\t\t%d\t\t%d\t\t%d", p[i], bt[i], wt[i], tat[i]);
    }

    avwt /= i;
    avtat /= i;
    printf("\n\nAverage Waiting Time: %f", avwt);
    printf("\nAverage Turnaround Time: %f", avtat);

    return 0;
}

RR（时间片轮转调度算法）：

#include<stdio.h>

int main()
{
    int i, n, qt, wt[20], tat[20], bt[20], rem_bt[20], time = 0;
    float avwt = 0, avtat = 0;

    printf("Enter total number of processes(maximum 20): ");
    scanf("%d", &n);

    printf("\nEnter Process Burst Time: \n");
    for(i = 0; i < n; i++)
    {
        printf("P[%d]: ", i+1);
        scanf("%d", &bt[i]);
        rem_bt[i] = bt[i];
    }

    printf("\nEnter Time Quantum: ");
    scanf("%d", &qt);

    while(1)
    {
        int flag = 0;
        for(i = 0; i < n; i++)
        {
            if(rem_bt[i] > 0)
            {
                flag = 1;
                if(rem_bt[i] > qt)
                {
                    time += qt;
                    rem_bt[i] -= qt;
                }
                else
                {
                    time += rem_bt[i];
                    wt[i] = time - bt[i];
                    rem_bt[i] = 0;
                }
            }
        }
        if(flag == 0)
            break;
    }

    for(i = 0; i < n; i++)
    {
        tat[i] = bt[i] + wt[i];
        avwt += wt[i];
        avtat += tat[i];
    }

    avwt /= i;
    avtat /= i;
    printf("\n\nAverage Waiting Time: %f", avwt);
    printf("\nAverage Turnaround Time: %f", avtat);

    return 0;
}