|
1 | 1 | /** |
2 | | - *@param {*[]}combinationOptions |
3 | | - *@param {number}combinationLength |
| 2 | + *@param {*[]}comboOptions |
| 3 | + *@param {number}comboLength |
4 | 4 | *@return {*[]} |
5 | 5 | */ |
6 | | - |
7 | | -exportdefaultfunctioncombineWithRepetitions(combinationOptions,combinationLength){ |
8 | | -// If combination length equal to 0 then return empty combination. |
9 | | -if(combinationLength===0){ |
10 | | -return[[]]; |
11 | | -} |
12 | | - |
13 | | -// If combination options are empty then return "no-combinations" array. |
14 | | -if(combinationOptions.length===0){ |
15 | | -return[]; |
| 6 | +exportdefaultfunctioncombineWithRepetitions(comboOptions,comboLength){ |
| 7 | +if(comboLength===1){ |
| 8 | +returncomboOptions.map(comboOption=>[comboOption]); |
16 | 9 | } |
17 | 10 |
|
18 | 11 | // Init combinations array. |
19 | 12 | constcombos=[]; |
20 | 13 |
|
21 | | -// Find all shorter combinations and attach head to each of those. |
22 | | -constheadCombo=[combinationOptions[0]]; |
23 | | -constshorterCombos=combineWithRepetitions(combinationOptions,combinationLength-1); |
| 14 | +// Eliminate characters one by one and concatenate them to |
| 15 | +// combinations of smaller lengths. |
| 16 | +for(letoptionIndex=0;optionIndex<comboOptions.length;optionIndex+=1){ |
| 17 | +constcurrentOption=comboOptions[optionIndex]; |
24 | 18 |
|
25 | | -for(letcombinationIndex=0;combinationIndex<shorterCombos.length;combinationIndex+=1){ |
26 | | -constcombo=headCombo.concat(shorterCombos[combinationIndex]); |
27 | | -combos.push(combo); |
28 | | -} |
| 19 | +constsmallerCombos=combineWithRepetitions( |
| 20 | +comboOptions.slice(optionIndex), |
| 21 | +comboLength-1, |
| 22 | +); |
29 | 23 |
|
30 | | -// Let's shift head to the right and calculate all the rest combinations. |
31 | | -constcombinationsWithoutHead=combineWithRepetitions( |
32 | | -combinationOptions.slice(1), |
33 | | -combinationLength, |
34 | | -); |
| 24 | +smallerCombos.forEach((smallerCombo)=>{ |
| 25 | +combos.push([currentOption].concat(smallerCombo)); |
| 26 | +}); |
| 27 | +} |
35 | 28 |
|
36 | | -// Join all combinations and return them. |
37 | | -returncombos.concat(combinationsWithoutHead); |
| 29 | +returncombos; |
38 | 30 | } |