How to save a matrix indexes [closed] - c

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Im practicing c and I have some trouble with this code :
I want to make a movie theatre ticket program.
The programs is getting a specific number evertime, and its seeking for the first free seats, if there are none it suppose to print a massage.
The seats must be attached to each other and in the same row.
The indexes of the seats need to be printed as well as mark as taken..
Im marking 1 as taken and 0 as untaken.
I need your help with how to save the indexes everytime.
#include <stdio.h>
#include <string.h>
main()
{
int i, j;
int Freeseats = 0;
int arr[10][20]= {{0}};
for(i=0; i<10; i++)
{
for(j=0; j<20; j++)
{
printf("%d", arr[i][j]);
}
printf("\n");
}
while(1)
{
int num, n=0;
scanf("%d",&num);
for(i=0; i<10; i++)
{
for(j=0; j<20; j++)
{
if(arr[i][j] == 0 && Freeseats < num)
{
Freeseats++;
}
else{
Freeseats = 0;
}
if(Freeseats == num)
{
}
}
}
}
}

Answer 1

I think your approach is wrong. You don't need to save any indexes.
Your task is to find a row where there is N consecutive free seats. So you need an extra loop where you count the number of consecutive free seats.
Something like:
#include <stdio.h>
#include <string.h>
#define SEATS_PER_ROW 20
#define ROWS 10
main()
{
int i, j, k, max;
int arr[ROWS][SEATS_PER_ROW]= {{0}};
for(i=0; i<10; i++)
{
for(j=0; j<20; j++)
{
printf("%d", arr[i][j]);
}
printf("\n");
}
while(1)
{
printf("Please enter the number of seats needed\n");
int num, n=0;
if (1 != scanf("%d",&num))
{
printf("Illegal input - stop program\n");
break;
}
printf("Searching for %d seats\n", num);
if (num > SEATS_PER_ROW)
{
printf("We don't have that many seats in a single row\n");
continue;
}
int found = 0;
for (i=0; i<10 && found != 1; i++)
{
found = 0;
for (j=0; j<(20-num+1) && found != 1; j++)
{
found = 0;
// Check for num consecutive free seats starting at i, j
for (k=0; k<num; k++)
{
if(arr[i][j+k] != 0)
{
// Can't sit here
found = -1;
break;
}
}
if (found == 0)
{
// We found a place - starting at i, j
// Mark them as used
found = 1;
printf("Seats assinged in row %d : seat %d to %d\n", i, j, j+num-1);
for(k=0; k<num; k++)
{
arr[i][j+k] = 1;
}
// Debug print
//for(i=0; i<10; i++)
//{
// for(j=0; j<20; j++)
// {
// printf("%d", arr[i][j]);
// }
// printf("\n");
//}
}
}
}
if (found != 1)
{
printf("So many seats are not available\n");
}
}
return 0;
}
With input:
10
15
2
6
20
3
21
9
The output is:
Please enter the number of seats needed
Searching for 10 seats
Seats assinged in row 0 : seat 0 to 9
Please enter the number of seats needed
Searching for 15 seats
Seats assinged in row 1 : seat 0 to 14
Please enter the number of seats needed
Searching for 2 seats
Seats assinged in row 0 : seat 10 to 11
Please enter the number of seats needed
Searching for 6 seats
Seats assinged in row 0 : seat 12 to 17
Please enter the number of seats needed
Searching for 20 seats
Seats assinged in row 2 : seat 0 to 19
Please enter the number of seats needed
Searching for 3 seats
Seats assinged in row 1 : seat 15 to 17
Please enter the number of seats needed
Searching for 21 seats
We don't have that many seats in a single row
Please enter the number of seats needed
Searching for 9 seats
Seats assinged in row 3 : seat 0 to 8
Please enter the number of seats needed
Searching for 15 seats
Seats assinged in row 4 : seat 0 to 14
See it at https://ideone.com/36zjuC