Non Preemptive Priority Algorithm in C

TheLazyBusyCoder's Blog

Welcome to my coding adventures! In this post, we'll explore a C program.

Exploring Non Preemptive Priority - scheduling algorithm in C

Check out my YouTube video explaining this code: No Video

   
    
        
#include <stdio.h>
#include

typedef struct process {
	int id , at , bt ,p,rt, ct , tat , wt;
} process;

void display(process proc[] , int n) {
	int i;
	printf("\n\nP  AT BT  P CT TAT WT\n");
	for(i = 0; i < n; i++) {
		printf("P%d %2d %2d %2d %2d %2d %2d\n" , 
			proc[i].id,
			proc[i].at,
			proc[i].bt,
			proc[i].p,
			proc[i].ct,
			proc[i].tat,
			proc[i].wt
		);
	}
}

void nonp(process proc[] , int n) {
	int p = n;
	int i  , j;
	int time = 0;
	while(p > 0) {
		int min = -1;
		for(i = 0; i < n; i++) {
			if(proc[i].at <= time && proc[i].rt > 0) {
				if(min == -1 || proc[i].p < proc[min].p) {
					min = i;
				}
			}
		}
		if(min == -1) time++;
		else {
			time += proc[min].rt;
			proc[min].ct = time;
			proc[min].rt = 0;
			p--;
		}
	}
	int ttat = 0;
	int twt = 0;
	for(i = 0; i < n; i++) {
		proc[i].tat = proc[i].ct - proc[i].at;
		proc[i].wt = proc[i].tat - proc[i].bt;
		ttat += proc[i].tat;
		twt += proc[i].wt;
	}
	display(proc , n);
	printf("\nAvg TAT %0.2f\nAvg WT %0.2f\n" , (ttat * 1.0) / n , (twt * 1.0)  / n);
}

int main() {
	int n;
	printf("Enter number of process: ");
	scanf(" %d" , &n);
	process proc[n];
	int i;
	for(i = 0; i < n; i++) {
		proc[i].id = i+1;
		printf("\nFor P%d\n", i+1);
		printf("Enter AT: ");
		scanf(" %d" , &proc[i].at);
		printf("Enter BT: ");
		scanf(" %d" , &proc[i].bt);
		printf("Enter P: ");
		scanf(" %d" , &proc[i].p);
		proc[i].rt = proc[i].bt;
		proc[i].ct = proc[i].tat = proc[i].wt = 0;
	}
	nonp(proc , n);
	return 0;
}

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