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JavaScript Binary Search [Khan Academy Challenge]
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/* Returns either the index of the location in the array, | |
or -1 if the array did not contain the targetValue */ | |
var doSearch = function(array, targetValue) { | |
var min = 0; | |
var max = array.length - 1; | |
var guess; | |
var i = 1; | |
while (max >= min){ | |
guess = Math.floor((max + min)/2); | |
if(array[guess] === targetValue){ | |
println("Total guesses " +i); | |
return guess; | |
} | |
else if (array[guess] < targetValue){ | |
min = guess +1; | |
} | |
else { | |
max = guess -1; | |
} | |
i = i+1; | |
println(guess); | |
} | |
return -1; | |
}; | |
var 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]; | |
//var result = doSearch(primes, 5); | |
//println("Found prime at index " + result); | |
Program.assertEqual(doSearch(primes, 73), 20); | |
Program.assertEqual(doSearch(primes, 97), 24); | |
Program.assertEqual(doSearch(primes, 2), 0); |
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