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Pascal's Triangle
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| // Generates Pascal's triangle of any number of rows | |
| // | |
| // https://en.wikipedia.org/wiki/Pascal%27s_triangle | |
| function nextRow(row) { | |
| const right = row.concat(0) | |
| const left = [0].concat(row) | |
| return left.map((x, i) => x + right[i]); | |
| } | |
| function triangle(row, rows) { | |
| if (rows === 0) { | |
| return []; | |
| } else { | |
| return [row, triangle(nextRow(row), rows-1)] | |
| } | |
| } | |
| function printPascal(arr){ | |
| return arr.reduce((acc, item, index) => { | |
| return index === 0 ? acc.concat([item]) : acc.concat(printPascal(item)) | |
| }, []) | |
| } | |
| printPascal(triangle([1], 5)) // [[1], [1, 1], [1, 2, 1], [1, 3, 3, 1], [1, 4, 6, 4, 1]] | |
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Snippet for a Pascal's Triangle function. Based on a common Scheme/ Lisp implementation.