Generate combinations for a Master Combo Padlock after a reset went wrong

master-lock-combo.js

// After resetting the Master Combo Lock I was unable to unlock it.
// Assuming that I had been off on one or more on the new number/
// letters I needed to generate all of the combinations so I could
// open it.

// This is an example of the combo I thought I set it to:
const combo = '0AT';

// These are the numbers/letters available on the dial:
const letters = '0123456789ADEHJLNRST';

// Find a letter/number before a given letter/number
function before(letter) {
  const index = letters.indexOf(letter);
  if(index === 0) {
    return letters[letters.length - 1];
  }
  return letters[index - 1];
}

// Find a letter/number after a given letter/number
function after(letter) {
  const index = letters.indexOf(letter);
  if(index === letters.length - 1) {
    return letters[0];
  }
  return letters[index + 1];
}

// We need an array of three letter/number combinations
// with the letters/numbers falling on either side of the
// combo we thought we had set.
// In our example we need:
// [ [ 'T', '0', '1' ], [ '9', 'A', 'D' ], [ 'S', 'T', '0' ] ]
const combos = combo.split('').map(letter => {
  return [
    before(letter), letter, after(letter)
  ]
});

console.log(combos);

for(let i = 0; i < 3; i++) {
  for(let j = 0; j < 3; j++) {
    for(let k = 0; k < 3; k++) {
      console.log(`${combos[0][i]}${combos[1][j]}${combos[2][k]}`);
    }
  }
}

/*
Example list of combos:

T9S
T9T
T90
TAS
TAT
TA0
TDS
TDT
TD0
09S
09T
090
0AS
0AT
0A0
0DS
0DT
0D0
19S
19T
190
1AS
1AT
1A0
1DS
1DT
1D0
*/