用c语言实现要求输入4个进程的信息，若进程调度采用抢占式动态优先级调度算法，cpu每过一个时间单位，运行态的进程优先数减一，而就绪态加一，并计算每个作业完成时间

在 C 语言中实现这样的功能，你需要首先创建结构体来存储进程信息，包括进程ID、优先级等属性。然后，你可以设计一个队列数据结构来存放进程，其中就绪队列和运行队列是两个部分。接下来，模拟抢占式调度算法的逻辑：

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

typedef struct {
    int pid;
    int priority;
    time_t start_time;
} Process;

#define MAX_PROCESSES 4
#define CPU_TIME_UNIT 1

// 定义队列
struct Queue {
    Process* processes;
    int front, rear;
};

void init_queue(struct Queue* queue) {
    queue->processes = malloc(MAX_PROCESSES * sizeof(Process));
    queue->front = -1;
    queue->rear = -1;
}

void enqueue(struct Queue* queue, Process p) {
    if (queue->rear == (queue->front + 1) % MAX_PROCESSES) {
        printf("Queue is full, cannot enqueue.\n");
        return;
    }
    queue->processes[++queue->rear] = p;
    if (queue->front == -1)
        queue->front = 0;
}

Process dequeue(struct Queue* queue) {
    if (queue->front == queue->rear)
        return (Process){-1, -1, -1}; // 返回空过程
    Process p = queue->processes[queue->front++];
    if (queue->front > queue->rear)
        queue->front = 0; // 修复循环引用
    return p;
}

// 抢占式调度函数
void preemptive_priority_scheduling(struct Queue* running, struct Queue* ready) {
    Process current = dequeue(running);
    if (current.pid != -1) { // 运行的进程结束
        current.end_time = time(NULL) - current.start_time;
        printf("Process %d completed in %d CPU time units.\n", current.pid, current.end_time);
        enqueue(ready, current); // 回到就绪队列
    } else {
        if (!ready->front) { // 如果就绪队列为空
            Process new_process = dequeue(ready); // 取出最高优先级
            enqueue(running, new_process); // 开始新的进程
        } else {
            Process new_process = dequeue(ready); // 拿走当前就绪队列最高优先级
            new_process.priority++; // 优先级增加
            enqueue(running, new_process); // 调度新的进程
        }
    }
}

int main() {
    struct Queue running, ready;
    init_queue(&running);
    init_queue(&ready);

    // 输入4个进程信息并分配初始优先级
    for (int i = 0; i < MAX_PROCESSES; ++i) {
        printf("Enter process %d details: PID, Priority\n", i+1);
        scanf("%d%d", &running.processes[i].pid, &running.processes[i].priority);
        running.processes[i].start_time = time(NULL); // 设置开始时间
        enqueue(ready, running.processes[i]); // 先入就绪队列
    }

    while (true) {
        preemptive_priority_scheduling(&running, &ready);
        sleep(CPU_TIME_UNIT); // 模拟CPU时间单位流逝
    }

    return 0;
}