一个c语言代码实现先来先服务调度算法、短作业优先算法、时间片轮转和优先级调度算法

先来先服务调度算法（FCFS）：

#include <stdio.h>
#define MAX 10

struct Process {
    int pid;
    int arrival_time;
    int burst_time;
    int waiting_time;
    int turnaround_time;
};

int main() {
    struct Process p[MAX];
    int n, i;
    float avg_waiting_time = 0, avg_turnaround_time = 0;

    printf("Enter the number of processes: ");
    scanf("%d", &n);
    for(i=0; i<n; i++) {
        printf("Enter arrival time and burst time for Process %d: ", i+1);
        scanf("%d %d", &p[i].arrival_time, &p[i].burst_time);
        p[i].pid = i+1;
    }

    // calculate waiting time and turnaround time
    p[0].waiting_time = 0;
    for(i=1; i<n; i++) {
        p[i].waiting_time = p[i-1].waiting_time + p[i-1].burst_time;
    }
    for(i=0; i<n; i++) {
        p[i].turnaround_time = p[i].waiting_time + p[i].burst_time;
        avg_waiting_time += p[i].waiting_time;
        avg_turnaround_time += p[i].turnaround_time;
    }

    // print result
    printf("\nProcess\tArrival Time\tBurst Time\tWaiting Time\tTurnaround Time\n");
    for(i=0; i<n; i++) {
        printf("%d\t\t%d\t\t%d\t\t%d\t\t%d\n", p[i].pid, p[i].arrival_time, p[i].burst_time, p[i].waiting_time, p[i].turnaround_time);
    }
    avg_waiting_time /= n;
    avg_turnaround_time /= n;
    printf("Average Waiting Time: %f\n", avg_waiting_time);
    printf("Average Turnaround Time: %f\n", avg_turnaround_time);

    return 0;
}

短作业优先算法（SJF）：

#include <stdio.h>
#define MAX 10

struct Process {
    int pid;
    int arrival_time;
    int burst_time;
    int waiting_time;
    int turnaround_time;
    int is_completed;
};

int main() {
    struct Process p[MAX];
    int n, i, j;
    float avg_waiting_time = 0, avg_turnaround_time = 0;

    printf("Enter the number of processes: ");
    scanf("%d", &n);
    for(i=0; i<n; i++) {
        printf("Enter arrival time and burst time for Process %d: ", i+1);
        scanf("%d %d", &p[i].arrival_time, &p[i].burst_time);
        p[i].pid = i+1;
        p[i].is_completed = 0;
    }

    int time = 0, completed = 0;
    while(completed != n) {
        int shortest = -1;
        for(i=0; i<n; i++) {
            if(!p[i].is_completed && p[i].arrival_time <= time) {
                if(shortest == -1 || p[i].burst_time < p[shortest].burst_time) {
                    shortest = i;
                }
            }
        }
        if(shortest != -1) {
            p[shortest].waiting_time = time - p[shortest].arrival_time;
            p[shortest].turnaround_time = p[shortest].waiting_time + p[shortest].burst_time;
            avg_waiting_time += p[shortest].waiting_time;
            avg_turnaround_time += p[shortest].turnaround_time;
            p[shortest].is_completed = 1;
            completed++;
            time += p[shortest].burst_time;
        } else {
            time++;
        }
    }

    // print result
    printf("\nProcess\tArrival Time\tBurst Time\tWaiting Time\tTurnaround Time\n");
    for(i=0; i<n; i++) {
        printf("%d\t\t%d\t\t%d\t\t%d\t\t%d\n", p[i].pid, p[i].arrival_time, p[i].burst_time, p[i].waiting_time, p[i].turnaround_time);
    }
    avg_waiting_time /= n;
    avg_turnaround_time /= n;
    printf("Average Waiting Time: %f\n", avg_waiting_time);
    printf("Average Turnaround Time: %f\n", avg_turnaround_time);

    return 0;
}

时间片轮转算法（RR）：

#include <stdio.h>
#define MAX 10

struct Process {
    int pid;
    int arrival_time;
    int burst_time;
    int remaining_time;
    int waiting_time;
    int turnaround_time;
    int is_completed;
};

int main() {
    struct Process p[MAX];
    int n, i, j, time_quantum;
    float avg_waiting_time = 0, avg_turnaround_time = 0;

    printf("Enter the number of processes: ");
    scanf("%d", &n);
    for(i=0; i<n; i++) {
        printf("Enter arrival time and burst time for Process %d: ", i+1);
        scanf("%d %d", &p[i].arrival_time, &p[i].burst_time);
        p[i].pid = i+1;
        p[i].remaining_time = p[i].burst_time;
        p[i].is_completed = 0;
    }

    printf("Enter time quantum: ");
    scanf("%d", &time_quantum);

    int time = 0, completed = 0;
    while(completed != n) {
        for(i=0; i<n; i++) {
            if(!p[i].is_completed && p[i].arrival_time <= time) {
                int execute_time = time_quantum;
                if(p[i].remaining_time < execute_time) {
                    execute_time = p[i].remaining_time;
                }
                p[i].remaining_time -= execute_time;
                time += execute_time;
                if(p[i].remaining_time == 0) {
                    p[i].waiting_time = time - p[i].arrival_time - p[i].burst_time;
                    if(p[i].waiting_time < 0) {
                        p[i].waiting_time = 0;
                    }
                    p[i].turnaround_time = p[i].waiting_time + p[i].burst_time;
                    avg_waiting_time += p[i].waiting_time;
                    avg_turnaround_time += p[i].turnaround_time;
                    p[i].is_completed = 1;
                    completed++;
                }
            }
        }
    }

    // print result
    printf("\nProcess\tArrival Time\tBurst Time\tWaiting Time\tTurnaround Time\n");
    for(i=0; i<n; i++) {
        printf("%d\t\t%d\t\t%d\t\t%d\t\t%d\n", p[i].pid, p[i].arrival_time, p[i].burst_time, p[i].waiting_time, p[i].turnaround_time);
    }
    avg_waiting_time /= n;
    avg_turnaround_time /= n;
    printf("Average Waiting Time: %f\n", avg_waiting_time);
    printf("Average Turnaround Time: %f\n", avg_turnaround_time);

    return 0;
}

优先级调度算法：

#include <stdio.h>
#define MAX 10

struct Process {
    int pid;
    int arrival_time;
    int burst_time;
    int priority;
    int waiting_time;
    int turnaround_time;
    int is_completed;
};

int main() {
    struct Process p[MAX];
    int n, i, j;
    float avg_waiting_time = 0, avg_turnaround_time = 0;

    printf("Enter the number of processes: ");
    scanf("%d", &n);
    for(i=0; i<n; i++) {
        printf("Enter arrival time, burst time and priority for Process %d: ", i+1);
        scanf("%d %d %d", &p[i].arrival_time, &p[i].burst_time, &p[i].priority);
        p[i].pid = i+1;
        p[i].is_completed = 0;
    }

    int time = 0, completed = 0;
    while(completed != n) {
        int highest_priority = -1, index = -1;
        for(i=0; i<n; i++) {
            if(!p[i].is_completed && p[i].arrival_time <= time) {
                if(p[i].priority > highest_priority) {
                    highest_priority = p[i].priority;
                    index = i;
                }
            }
        }
        if(index != -1) {
            p[index].waiting_time = time - p[index].arrival_time;
            p[index].turnaround_time = p[index].waiting_time + p[index].burst_time;
            avg_waiting_time += p[index].waiting_time;
            avg_turnaround_time += p[index].turnaround_time;
            p[index].is_completed = 1;
            completed++;
            time += p[index].burst_time;
        } else {
            time++;
        }
    }

    // print result
    printf("\nProcess\tArrival Time\tBurst Time\tPriority\tWaiting Time\tTurnaround Time\n");
    for(i=0; i<n; i++) {
        printf("%d\t\t%d\t\t%d\t\t%d\t\t%d\t\t%d\n", p[i].pid, p[i].arrival_time, p[i].burst_time, p[i].priority, p[i].waiting_time, p[i].turnaround_time);
    }
    avg_waiting_time /= n;
    avg_turnaround_time /= n;
    printf("Average Waiting Time: %f\n", avg_waiting_time);
    printf("Average Turnaround Time: %f\n", avg_turnaround_time);

    return 0;
}