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_javascript-findBinary.js - also has findIndexBinary
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| function findBinary(arr, num, ixmin=0, ixmax) { | |
| // arr MUST be sorted!!! and only numbers!!! duh! see: https://en.wikipedia.org/wiki/Binary_search_algorithm | |
| // ixmin and ixmax are programtic use only, meaning devuser should NEVER supply value for it | |
| if (ixmax === undefined) ixmax = arr.length; | |
| let ixmid = Math.floor((ixmax-ixmin)/2) + ixmin; | |
| let elmid = arr[ixmid]; | |
| if (elmid === num) return elmid; | |
| else { | |
| if (ixmax - ixmin === 1) return null; // not found | |
| return num < elmid ? findBinary(arr, num, ixmin, ixmid) : findBinary(arr, num, ixmid, ixmax); | |
| } | |
| } | |
| function findIndexBinary(arr, num, ixmin=0, ixmax) { | |
| // arr MUST be sorted!!! and only numbers!!! duh! see: https://en.wikipedia.org/wiki/Binary_search_algorithm | |
| // ixmin and ixmax are programtic use only, meaning devuser should NEVER supply value for it | |
| if (ixmax === undefined) ixmax = arr.length; | |
| let ixmid = Math.floor((ixmax-ixmin)/2) + ixmin; | |
| let elmid = arr[ixmid]; | |
| if (elmid === num) return ixmid; | |
| else { | |
| if (ixmax - ixmin === 1) return null; // not found | |
| return num < elmid ? findIndexBinary(arr, num, ixmin, ixmid) : findIndexBinary(arr, num, ixmid, ixmax); | |
| } | |
| } |
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findIndexBinary