spiralprint.c

#include <stdio.h>
#include <malloc.h>

// Spiral traversal of matrices / 2D arrays

// The algorithm starts from the top left corner of the array, and traverses the first row from left to right.
// Once complete, it traverses the rightmost column top to bottom.
// Next, the algorithm traverses the bottommost row.
// Lastly, the algorithm traverses the leftmost column.
// Now the algorithm continues again for inner elements which are left in similar manner

void spiralPrint(int **matrix,int m,int n) {
    int i=0,j=0,num=1;
    int counter1=n,counter2=m;
    while (counter1 > 0 || counter2>0) {
        if (m == n && counter1==1) {
            printf("%d ",matrix[n/2][n/2]);
        } else {
            int k;
            for (k=1;k<counter1;k++) {
                printf("%d ",matrix[i][j++]);
            }
            for (k=1;k<counter2;k++) {
                printf("%d ",matrix[i++][j]);
            }
            for (k=1;k<counter1;k++) {
                printf("%d ",matrix[i][j--]);
            }
            for (k=1;k<counter2;k++) {
                printf("%d ",matrix[i--][j]);
            }
            i++;j++;
        }
        counter1-=2;
        counter2-=2;
    }
}

int main() {
    int m,n;
    printf("Enter no of rows and columns: ");
    scanf("%d %d",&m,&n);

    int **matrix = (int **)malloc(sizeof(int *)*m);
    for (int i=0;i<m;i++) {
        matrix[i] = (int *)malloc(sizeof(int)*n);
        printf("Enter elements of row %d: ",i+1);
        for (int j=0;j<n;j++) {
            scanf("%d",&matrix[i][j]);
        }
    }

    printf("Spiral Traversal looks like: ");
    spiralPrint(matrix,m,n);
    
    printf("\n");
    return 0;
}