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Write a program to take a number N as an input
and then it has to print from 1 to N in a spiral shape
Ex: input 9
1 2 3

8 9 4

7 6 5
Posted

1 solution

This should explain the algorithm

C#
// function to print the top-right peel of the matrix and
// recursively call the print bottom-left on the submatrix.
void printTopRight(int a[][COL], int x1, int y1, int x2, int y2) {
    int i = 0, j = 0;

    // print values in the row.
    for(i = x1; i<=x2; i++) {
        printf("%d ", a[y1][i]);
    }

    // print values in the column.
    for(j = y1 + 1; j <= y2; j++)         {
        printf("%d ", a[j][x2]);
    }

    // see if more layers need to be printed.
    if(x2-x1 > 0) {
        // if yes recursively call the function to
        // print the bottom left of the sub matrix.
        printBottomLeft(a, x1, y1 + 1, x2-1, y2);
    }
}

// function to print the bottom-left peel of the matrix and
// recursively call the print top-right on the submatrix.
void printBottomLeft(int a[][COL], int x1, int y1, int x2, int y2) {
    int i = 0, j = 0;

    // print the values in the row in reverse order.
    for(i = x2; i>=x1; i--) {
        printf("%d ", a[y2][i]);
    }

    // print the values in the col in reverse order.
    for(j = y2 - 1; j >= y1; j--) {
        printf("%d ", a[j][x1]);
    }

    // see if more layers need to be printed.
    if(x2-x1 > 0) {
        // if yes recursively call the function to
        // print the top right of the sub matrix.
        printTopRight(a, x1+1, y1, x2, y2-1);
    }
}

void printSpiral(int arr[][COL]) {
    printTopRight(arr,0,0,COL-1,ROW-1);
    printf("\n");
}
 
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