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[逻辑推理选择专项练习题]逻辑推理笔试选择专项练习1:数字推理：0 ，6 ，78 ，_____ ，15620A.240B.252C.1020D.77712:你可以随时愚弄某些人。假若以上属实，以下哪些判断必然为真?Ⅰ. 张三和李四随时都可能被你...+阅读

Problem Statement

A simple line drawing program uses a blank 20 x 20 pixel canvas and a directional cursor that starts at the upper left corner pointing straight down. The upper left corner of the canvas is at (0, 0) and the lower right corner is at (19, 19). You are given a String[], mands, each element of which contains one of two possible mands. A mand of the form FORWARD x means that the cursor should move forward by x pixels. Each pixel on its path, including the start and end points, is painted black. The only other mand is LEFT, which means that the cursor should change its direction by 90 degrees counterclockwise. So, if the cursor is initially pointing straight down and it receives a single LEFT mand, it will end up pointing straight to the right. Execute all the mands in order and return the resulting 20 x 20 pixel canvas as a String[] where character j of element i represents the pixel at (i, j). Black pixels should be represented as uppercase 'X' characters and blank pixels should be represented as '.' characters.

Definition

Class:

DrawLines

Method:

execute

Parameters:

String[]

Returns:

String[]

Method signature:

String[] execute(String[] mands)

(be sure your method is public)

????

Notes

The cursor only paints the canvas if it moves (see example 1).

Constraints

mands will contain between 1 and 50 elements, inclusive.

Each element of mands will be formatted as either LEFT or FORWARD x (quotes for clarity only), where x is an integer between 1 and 19, inclusive, with no extra leading zeros.

When executing the mands in order, the cursor will never lee the 20 x 20 pixel canvas.

Examples

????

{FORWARD 19, LEFT, FORWARD 19, LEFT, FORWARD 19, LEFT, FORWARD 19}

Returns:

{XXXXXXXXXXXXXXXXXXXX,

X..................X,

XXXXXXXXXXXXXXXXXXXX }

This sequence of mands draws a 20 x 20 outline of a square. The cursor is initially at (0, 0) pointing straight down. It then trels to (0, 19) after the first FORWARD mand, painting each pixel along its path with a '*'. It then rotates 90 degrees left, trels to (19, 19), rotates 90 degrees left, trels to (19, 0), rotates 90 degrees left, and finally trels back to (0, 0).

????

{LEFT, LEFT, LEFT, LEFT, LEFT, LEFT, LEFT, LEFT}

Returns:

{....................,