3.4 KiB
3.4 KiB
title | id | challengeType |
---|---|---|
Gray code | 5a23c84252665b21eecc7e80 | 5 |
Description
Encoding (MSB is bit 0, b is binary, g is Gray code):
if b[i-1] = 1
g[i] = not b[i]
else
g[i] = b[i]
Or: g = b xor (b logically right shifted 1 time)
Decoding (MSB is bit 0, b is binary, g is Gray code):
b[0] = g[0]
for other bits:
b[i] = g[i] xor b[i-1]
Instructions
Tests
tests:
- text: <code>gray</code> should be a function.
testString: assert(typeof gray=='function','<code>gray</code> should be a function.');
- text: <code>gray(true,177)</code> should return a number.
testString: assert(typeof gray(true,177)=='number','<code>gray(true,177)</code> should return a number.');
- text: <code>gray(true,177)</code> should return <code>233</code>.
testString: assert.equal(gray(true,177),233,'<code>gray(true,177)</code> should return <code>233</code>.');
- text: <code>gray(true,425)</code> should return <code>381</code>.
testString: assert.equal(gray(true,425),381,'<code>gray(true,425)</code> should return <code>381</code>.');
- text: <code>gray(true,870)</code> should return <code>725</code>.
testString: assert.equal(gray(true,870),725,'<code>gray(true,870)</code> should return <code>725</code>.');
- text: <code>gray(false,233)</code> should return <code>177</code>.
testString: assert.equal(gray(false,233),177,'<code>gray(false,233)</code> should return <code>177</code>.');
- text: <code>gray(false,381)</code> should return <code>425</code>.
testString: assert.equal(gray(false,381),425,'<code>gray(false,381)</code> should return <code>425</code>.');
- text: <code>gray(false,725)</code> should return <code>870</code>.
testString: assert.equal(gray(false,725),870,'<code>gray(false,725)</code> should return <code>870</code>.');
Challenge Seed
function gray(enc, number) {
// Good luck!
}
Solution
function gray(enc, number){
if(enc){
return number ^ (number >> 1);
}else{
let n = number;
while (number >>= 1) {
n ^= number;
}
return n;
}
}