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Direktori : /usr/share/nodejs/binary-search/ |
Current File : //usr/share/nodejs/binary-search/index.js |
module.exports = function(haystack, needle, comparator, low, high) { var mid, cmp; if(low === undefined) low = 0; else { low = low|0; if(low < 0 || low >= haystack.length) throw new RangeError("invalid lower bound"); } if(high === undefined) high = haystack.length - 1; else { high = high|0; if(high < low || high >= haystack.length) throw new RangeError("invalid upper bound"); } while(low <= high) { // The naive `low + high >>> 1` could fail for array lengths > 2**31 // because `>>>` converts its operands to int32. `low + (high - low >>> 1)` // works for array lengths <= 2**32-1 which is also Javascript's max array // length. mid = low + ((high - low) >>> 1); cmp = +comparator(haystack[mid], needle, mid, haystack); // Too low. if(cmp < 0.0) low = mid + 1; // Too high. else if(cmp > 0.0) high = mid - 1; // Key found. else return mid; } // Key not found. return ~low; }