## CSci 1301: Lab 6

You may work in groups of 2 or 3 (preferred) or individually.

#### What to submit

At the end of the lab please send me **and your group partner(s)** all your Scheme files as e-mail attachments. My e-mail is elenam at morris.umn.edu. The subject of your e-mail must be "1301 Lab 6" followed by "Final" or "Not final", depending on whether this is a final submission or you are still working on it. If you need to finish it, make sure to set up a time with your group partner(s) to finish the lab.

#### When to submit

Due Friday, October 23rd, at 11:59pm. If you submit the final version during the lab, you are done.

### Problem 1 (10 points)

Write a function `draw-stairs`

that draws a "staircase" of a
given color. More precisely, the function has the following header:

```
(define (draw-stairs left-upper n width height color)
...
)
```

where `left-upper`

is the position of the left-upper corner of the staircase,
`n`

is the number of steps that remain to be drawn, `width`

is the width of one stair, `height`

is the
height of a step, and `color`

is the color of the staircase.

Below is an example:

```
(draw-stairs (make-posn 10 10) 8 40 40 'green)
```

### Problem 2: Checker board (12 points)

Write a function `checker-board`

that takes draws an 8-by-8
checker board of two colors. More precisely, the function is defined as

```
(define (checker-board left-upper n side color1 color2))
```

Here `left-upper`

is the position of the left-upper corner of the board, `n`

is the number of rows that remain to be drawn, `side`

is the side of a square, `color1`

is the starting color for the row, and `color2`

is the alternating color.

The function requires **a "helper" function draw-row** that
draws one row of the board. Write and test the helper function first. Think
of what parameters it needs (what is its base case?).

CSci 1301
course web site.

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