26 lines
739 B
Markdown
26 lines
739 B
Markdown
---
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title: Partial sum array
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type: snippet
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language: javascript
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tags: [math]
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author: chalarangelo
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cover: river-house-lights
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dateModified: 2022-01-30T13:10:13+02:00
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---
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Creates an array of partial sums.
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- Use `Array.prototype.reduce()`, initialized with an empty array accumulator to iterate over `nums`.
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- Use `Array.prototype.slice()` to get the previous partial sum or `0` and add the current element to it.
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- Use the spread operator (`...`) to add the new partial sum to the accumulator array containing the previous sums.
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```js
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const accumulate = (...nums) =>
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nums.reduce((acc, n) => [...acc, n + (acc.slice(-1)[0] || 0)], []);
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```
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```js
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accumulate(1, 2, 3, 4); // [1, 3, 6, 10]
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accumulate(...[1, 2, 3, 4]); // [1, 3, 6, 10]
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```
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