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add bsearch

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This commit is contained in:
Justin Lin
2020-03-13 09:42:36 +08:00
parent f6b9b4b0c5
commit e6c4ffc117
1 changed files with 16 additions and 0 deletions
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src/util/bsearch.scad Normal file
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function _greaterThan(elem1, elem2, i) =
i == -1 ? false :
elem1[i] > elem2[i] ? true :
elem1[i] == elem2[i] ? _greaterThan(elem1, elem2, i - 1) : false;
function greaterThan(elem1, elem2) = _greaterThan(elem1, elem2, len(elem1));
function lessThan(elem1, elem2) = !greaterThan(elem1, elem2) && elem1 != elem2;
function _binary_search(sorted, elem, low, upper) =
low > upper ? -1 :
let(mid = floor((low + upper) / 2))
lessThan(sorted[mid], elem) ? _binary_search(sorted, elem, mid + 1, upper) :
greaterThan(sorted[mid], elem) ? _binary_search(sorted, elem, low, mid - 1) : mid;
function bsearch(sorted, elem) = _binary_search(sorted, elem, 0, len(sorted) - 1);