Q. Spiral Traversal of a nxn matrix where n is odd..

Well  this  is  a  really  good  question  for  your  coding  practice. This  is asked  in  many  interviews  to  check  the  coding  abilities  of  the  candidiates

Lets  have  a  5x5  matrix  as  an  example


0 1 2 3 4

5 6 7 8 9

10 11 12 13 14

15 16 17 18 19

20 21 22 23 24



for  this  answer  should  be
0 1 2 3 4 9 14 19 24 23 22 21 20 15 10 5 6 7 8 13 18 17 16 11 12

Time  Complexity=O(n)
Space Complexity=O(1)


#include<stdio.h>

int main()
{
int n=5;
int arr[n][n];
int top=0,bottom=n,left=0,right=n;//these  are  the  boundaries  of  the  matrix  while  traversing  spirally
int currX=0,currY=0;//these  are  the  locations  which  are  being  traversed

//arr  is  having  value  0 to 48  in  row  majority  order
for(int k=0;k<n;k++)
for(int k1=0;k1<n;k1++)
arr[k][k1]=n*k+k1;

// this is for printing matrix value
/*for(int k=0;k<n;k++)
{
for(int k1=0;k1<n;k1++)
printf("%d\t",arr[k][k1]);
printf("\n");
}*/


while((currX!=n/2)&&(currY!=n/2))
{
//printf("%d %d %d %d\n",left,right,top,bottom);
while(currX<right)
{printf("%d\t",arr[currY][currX]);currX++;}right--;currX--;currY++;top++;

while(currY<bottom)
{printf("%d\t",arr[currY][currX]);currY++;}bottom--;currY--;currX--;

while(currX>=left)
{printf("%d\t",arr[currY][currX]);currX--;}left++;currX++;currY--;

while(currY>=top)
{printf("%d\t",arr[currY][currX]);currY--;}currY++;currX++;
}
printf("%d",arr[n/2][n/2]);
return 0;
}