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December 28, 2018 01:18
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| function arrayToList(arr) { | |
| let list = {} | |
| let pointer = list; | |
| let end = arr.length - 1; | |
| for (let i = 0; i < end; i++) { | |
| let current = arr[i]; | |
| pointer.value = current; | |
| pointer.rest = {}; | |
| pointer = pointer.rest; | |
| } | |
| pointer.value = arr[end]; | |
| pointer.rest = null; | |
| return list; | |
| } | |
| function listToArray(list) { | |
| if (list.rest === null) { | |
| return [list.value]; | |
| } | |
| const newArr = listToArray(list.rest); | |
| newArr.unshift(list.value); | |
| return newArr; | |
| } | |
| function listToArrayWhile(list) { | |
| let arr = []; | |
| let pointer = list; | |
| while (pointer.rest !== null) { | |
| arr.push(pointer.value); | |
| pointer = pointer.rest; | |
| } | |
| arr.push(pointer.value); | |
| return arr; | |
| } | |
| function prepend(elem, list) { | |
| if (list.rest === null) { | |
| list.rest = { value: elem, rest: null }; | |
| return { value: list.value, rest: { | |
| value: elem, | |
| rest: null, | |
| } | |
| }; | |
| } | |
| return { value: list.value, rest: prepend(elem, list.rest) }; | |
| } | |
| function nth(num, list) { | |
| if (num === 0) { | |
| return list; | |
| } | |
| return nth(num - 1, list.rest); | |
| } | |
| const list = arrayToList([1, 2, 3, 4, 5]); | |
| console.log(list); | |
| const arr = listToArrayWhile(list); | |
| console.log(arr); | |
| const longerList = (prepend(0, list)); | |
| console.log(longerList); | |
| const third = nth(2, longerList); | |
| console.log(third); |
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