Binary Search
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/* Returns either the index of the location in the array,
or -1 if the array did not contain the targetValue */
'use strict';
const doSearch = (array, targetValue) => {
let min = 0;
let max = array.length - 1;
let guess;
while (min <= max) {
guess = (min + max) / 2 | 0;
if (array[guess] > targetValue) {
max = guess - 1;
} else if (array[guess] < targetValue) {
min = guess + 1;
} else {
return guess;
}
}
return -1;
};
const primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37,
41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97];
const result = doSearch(primes, 61);
console.log(`Found prime at index ${result}`);
JavaScript
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