Ethan’s 2 solutions of expressing pieces on Chinese chess board

Golden Thumb

Oct 2, 2019·4 min read

Ethan just wrote the embedded for loops to print out 90 points of an empty Chinese chess board.

for j in 0..<10 {
    for i in 0..<9 {
        desc = desc + " ."
    }
    desc = desc + "\n"
}

It looked like:

 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .

Next, what could we use to represent pieces on it?

To kick off our discussion, I wrote the following for him.

 r: red
 b: black
 
 r: rook 车（城堡）
 n: knight 马（骑士）
 b: bishop 象（大主教）
 w: warrior 士（勇士）rb
 k: king 将（国王）
 c: cannon 炮（加农炮）
 p: pawn 卒（小兵）

Ethan came with an idea in no time: “I would use 2 letters for each piece.”

“Do you mean something like this?”, I tried to confirm that I did get it.

 rrrn. . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 brbn. . . . . . .

“Yes”, he said.

“OK, I’ll leave it to you then”, I passed the control of screen to him.

He carefully deployed all the pieces, with nice spaces added also.

 rr rn rb rw rk rw rb rn rr
 .  .  .  .  .  .  .  .  .
 .  rc .  .  .  .  .  rc .
 rp .  rp .  rp .  rp .  rp
 .  .  .  .  .  .  .  .  .
 .  .  .  .  .  .  .  .  .
 bp .  bp .  bp .  bp .  bp
 .  bc .  .  .  .  .  bc .
 .  .  .  .  .  .  .  .  .
 br bn bb bw bk bw bb bn br

Class was over.

Here was the homework for him: “@Ethan HW: work out some different plans to use letters or numbers to show 32 pieces. You can talk with your friends or family. Try to find the best solution”.

A few minutes later, Ethan posted his 2nd option in WeChat.

I was happy with that. So I went on with: “@Ethan keep trying to see if you can find a solution with only a single letter, instead of two, for each piece. Post it here when you have one. So far both the solutions need 2 letters for each piece”.

Then a voice message came from the other end: “Sure, Uncle. I’ll think about the other solutions. But it’s late now and I would go to sleep”.

We met again in the next class. Ethan told me: “I failed to figure out any way with a single letter”. I said: “no worry. I actually like your 2nd solution, which uses digits. Let me make a copy of it”. So I went on and copied those text.

 r3 r4 r5 r6 r7 r6 r5 r4 r3
 .  .  .  .  .  .  .  .  .
 .  r2 .  .  .  .  .  r2 .
 r1 .  r1 .  r1 .  r1 .  r1
 .  .  .  .  .  .  .  .  .
 .  .  .  .  .  .  .  .  .
 b1 .  b1 .  b1 .  b1 .  b1
 .  b2 .  .  .  .  .  b2 .
 .  .  .  .  .  .  .  .  .
 b3 b4 b5 b6 b7 b6 b5 b4 b3

Ethan was proud of his work and shouted: “you forget to copy the part above it.”

 1=p
 2=c
 3=r
 4=n
 5=b
 6=w
 7=k

Oops, I didn’t realize the weight of his hard work. Every char matters in kids’ heart.

OK, it was time to reward his hard work. So I provided the final hint: “Do you know in English there are lower case and upper case?”

A few seconds passed in silence.

Then Ethan spoke loudly: “I got it!” This is the final version:

 R N B W K W B N R
 . . . . . . . . .
 . C . . . . . C .
 P . P . P . P . P
 . . . . . . . . .
 . . . . . . . . .
 p . p . p . p . p
 . c . . . . . c .
 . . . . . . . . .
 r n b w k w b n r