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  1. Prepare
  2. C
  3. Conditionals and Loops
  4. Printing Pattern Using Loops
  5. Discussions

Printing Pattern Using Loops

  • [deleted]     + 3 comments

    With this kind of problems, I always think about separating it into several shapes. Here's what I do with this problem:

    void print_upper_part( int n )
{
    int i,j,k,m;
    
    for( i = n; i >= 1 ; i-- ){
        // generate left triangle of numbers
        // the shape is somethin like:
        // *
        // **
        // ***
        // ****
        // *****
        for( j = n; j >= i; j-- ){
            printf("%d ",j);
        }
        // use the value before the last decrement
        j++;
        // generate the reverse pyramid using value of j
        // the shape is something like:
        // *******
        //  *****
        //   ***
        //    *
        for( k = 1; k <= (2*j) - 3; k++  ){
            printf("%d ",j);
        }
        // avoid printing 1 again since 1 has been printed at the left triangle
        j = j == 1 ? 2 : j;
        // generate right triangle of numbers
        // the shape is somethin like:
        //     *
        //    **
        //   ***
        //  ****
        // *****
        for( m = j; m <= n; m++ ){
            printf("%d ",m);
        }
        printf("\n");
    }
}

void print_lower_part( int n )
{
    int i,j,k,m;
    
    for( i = 2; i <= n ; i++ ){
        // generate left triangle of numbers
        // the shape is somethin like:
        // *****
        // ****
        // ***
        // **
        // *
        for( j = n; j >= i; j-- ){
            printf("%d ",j);
        }
        // use the value before the last decrement
        j++;
        // generate the pyramid using value of j
        // the shape is something like:
        //    *  
        //   ***
        //  *****
        // *******
        for( k = 1; k <= (2*j) - 3; k++ ){
            printf("%d ",j);
        }
        // generate right triangle of numbers
        // the shape is somethin like:
        // *****
        //  ****
        //   ***
        //    **
        //     *
        for( m = i; m <= n; m++ ){
            printf("%d ",m);
        }
        printf("\n");
    }
}