SJF scheduling algorithm in C

sjf.c

#include<stdio.h> 
//Sorting in increasing order of arrival time
void arrangeArrival(int num, int mat[][6]) 
{ 
	for(int i=0; i<num; i++) 
	{ 
		for(int j=0; j<num-i-1; j++) 
		{ 
			if(mat[j][1] > mat[j+1][1]) 
			{ 
				for(int k=0; k<5; k++) 
				{ 
					int tmp=mat[j][1];
                    				mat[j][1]=mat[j+1][1];
                    				mat[j][1]=tmp;
				} 
			} 
		} 
	} 
} 
void completionTime(int num, int mat[][6]) 
{ 
	int temp, val; 
	mat[0][3] = mat[0][1] + mat[0][2]; 
	mat[0][5] = mat[0][3] - mat[0][1]; 
	mat[0][4] = mat[0][5] - mat[0][2]; 
	
	for(int i=1; i<num; i++) 
	{ 
		temp = mat[i-1][3]; 
		int low = mat[i][2]; 
		for(int j=i; j<num; j++) 
		{ 
			if(temp >= mat[j][1] && low >= mat[j][2]) 
			{ 
				low = mat[j][2]; 
				val = j; 
			} 
		} 
		mat[val][3] = temp + mat[val][2]; 
		mat[val][5] = mat[val][3] - mat[val][1]; 
		mat[val][4] = mat[val][5] - mat[val][2]; 
		for(int k=0; k<6; k++) 
		{ 
			int tmp=mat[val][k];
            mat[val][k]=mat[i][k];
            mat[i][k]=tmp; 
		} 
	} 
} 

int main() 
{ 
	int num, temp; 
	
    //Number of processes
	num=4;

    //Matrix in order of process_id, arrival_time, burst_time
    int mat[][6]={{1,2,3,0,0,0},{2,0,4,0,0,0},{3,4,2,0,0,0},{4,5,4,0,0,0}}; 
	
	printf("Before arranging \n");
	for(int i=0; i<num; i++) 
	{ 
		printf("Process id: %d \n",mat[i][0]);
        printf("Arrival time: %d \n",mat[i][1]);
        printf("Burst time: %d \n",mat[i][2]);
	} 
	
	arrangeArrival(num, mat); 
	completionTime(num, mat); 

	printf("\n\nAfter arranging \n");
	for(int i=0; i<num; i++) 
	{ 
		printf("Process id: %d \n",mat[i][0]);
        printf("Arrival time: %d \n",mat[i][1]);
        printf("Burst time: %d \n",mat[i][2]);
        printf("Waiting time: %d \n",mat[i][4]);
        printf("Turnaround time: %d \n",mat[i][5]);
	} 
}