33 lines
793 B
JavaScript
33 lines
793 B
JavaScript
export default class HintKeyProducer {
|
|
constructor(charset) {
|
|
if (charset.length === 0) {
|
|
throw new TypeError('charset is empty');
|
|
}
|
|
|
|
this.charset = charset;
|
|
this.counter = [];
|
|
}
|
|
|
|
produce() {
|
|
this.increment();
|
|
|
|
return this.counter.map((x) => this.charset[x]).join('');
|
|
}
|
|
|
|
increment() {
|
|
let max = this.charset.length - 1;
|
|
if (this.counter.every((x) => x == max)) {
|
|
this.counter = new Array(this.counter.length + 1).fill(0);
|
|
return;
|
|
}
|
|
|
|
this.counter.reverse();
|
|
let len = this.charset.length;
|
|
let num = this.counter.reduce((x,y,index) => x + y * (len ** index)) + 1;
|
|
for (let i = 0; i < this.counter.length; ++i) {
|
|
this.counter[i] = num % len;
|
|
num = ~~(num / len);
|
|
}
|
|
this.counter.reverse();
|
|
}
|
|
}
|