28 lines
830 B
Markdown
28 lines
830 B
Markdown
---
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title: isSorted
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tags: array,intermediate
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---
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Returns `1` if the array is sorted in ascending order, `-1` if it is sorted in descending order or `0` if it is not sorted.
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Calculate the ordering `direction` for the first two elements.
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Use `Object.entries()` to loop over array objects and compare them in pairs.
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Return `0` if the `direction` changes or the `direction` if the last element is reached.
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```js
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const isSorted = arr => {
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let direction = -(arr[0] - arr[1]);
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for (let [i, val] of arr.entries()) {
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direction = !direction ? -(arr[i - 1] - arr[i]) : direction;
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if (i === arr.length - 1) return !direction ? 0 : direction / Math.abs(direction);
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else if ((val - arr[i + 1]) * direction > 0) return 0;
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}
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};
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```
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```js
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isSorted([0, 1, 2, 2]); // 1
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isSorted([4, 3, 2]); // -1
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isSorted([4, 3, 5]); // 0
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```
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