-
-
Notifications
You must be signed in to change notification settings - Fork 225
/
charset.js
53 lines (45 loc) · 1.02 KB
/
charset.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
"use strict";
const CHARSET = ("abcdefghijklmnopqrstuvwxyz" +
"ABCDEFGHIJKLMNOPQRSTUVWXYZ$_").split("");
module.exports = class Charset {
constructor(shouldConsider) {
this.shouldConsider = shouldConsider;
this.chars = CHARSET.slice();
this.frequency = {};
this.chars.forEach(c => {
this.frequency[c] = 0;
});
this.finalized = false;
}
consider(str) {
if (!this.shouldConsider) {
return;
}
str.split("").forEach(c => {
if (this.frequency[c] != null) {
this.frequency[c]++;
}
});
}
sort() {
if (this.shouldConsider) {
this.chars = this.chars.sort(
(a, b) => this.frequency[b] - this.frequency[a]
);
}
this.finalized = true;
}
getIdentifier(num) {
if (!this.finalized) {
throw new Error("Should sort first");
}
let ret = "";
num++;
do {
num--;
ret += this.chars[num % this.chars.length];
num = Math.floor(num / this.chars.length);
} while (num > 0);
return ret;
}
};