23 lines
965 B
Markdown
23 lines
965 B
Markdown
---
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title: initializeArrayWithRangeRight
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tags: array,math,intermediate
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---
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Initializes an array containing the numbers in the specified range (in reverse) where `start` and `end` are inclusive with their common difference `step`.
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Use `Array.from(Math.ceil((end+1-start)/step))` to create an array of the desired length(the amounts of elements is equal to `(end-start)/step` or `(end+1-start)/step` for inclusive end), `Array.prototype.map()` to fill with the desired values in a range.
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You can omit `start` to use a default value of `0`.
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You can omit `step` to use a default value of `1`.
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```js
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const initializeArrayWithRangeRight = (end, start = 0, step = 1) =>
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Array.from({ length: Math.ceil((end + 1 - start) / step) }).map(
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(v, i, arr) => (arr.length - i - 1) * step + start
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);
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```
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```js
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initializeArrayWithRangeRight(5); // [5,4,3,2,1,0]
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initializeArrayWithRangeRight(7, 3); // [7,6,5,4,3]
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initializeArrayWithRangeRight(9, 0, 2); // [8,6,4,2,0]
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``` |