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var range = function(min, max) { | |
arr = []; | |
for (var i = min; i <= max; i++) { | |
arr.push(i); | |
} | |
return arr; | |
} | |
var fbMod = function(n) { | |
var msg = ''; | |
var result = new Array(n); | |
for (var i=1; i <= n; i++, msg='') { | |
(i % 3) || (msg += 'fizz'); | |
(i % 5) || (msg += 'buzz'); | |
result[i-1] = msg || i; | |
} | |
return result; | |
} | |
var binarySearch = function(value, arr) { // arr must be sorted | |
var low = -1; | |
var high = arr.length; | |
while (high - low > 1) { | |
var mid = Math.floor((low + high)/2); | |
(arr[mid] < value) ? low = mid : high = mid; | |
} | |
return high; | |
} | |
// helper function | |
var binaryInsert = function(itm, arr) { | |
var index = binarySearch(itm, arr); | |
if (itm === arr[index]) return arr; | |
arr.splice(index, 0, itm); | |
return arr; | |
} | |
// helper function | |
var random = function(min, max) { | |
return Math.floor((Math.random() * (1 + max - min)) + min); | |
} | |
var fisherYates = function(arr) { // mutates input! | |
var j, tmp; | |
for (var i = arr.length - 1; i > 0; i--) { | |
j = random(0, i); | |
tmp = arr[i]; | |
arr[i] = arr[j]; | |
arr[j] = tmp; | |
} | |
} | |
// randomly draws n unique integers between min and max (inclusive) | |
var draw = function(n, min, max) { | |
if (n > (1 + max - min)) throw new Error('draw: range too small'); | |
var result = []; | |
while (result.length < n) { | |
binaryInsert(random(min, max), result); | |
} | |
return result; | |
} | |
var powerSet = function(arr) { | |
var result = [[]]; | |
for (var i=0; i < arr.length; i++) { | |
for (var j=0, len=result.length; j < len; j++) { | |
result.push(result[j].concat(arr[i])); | |
} | |
} | |
return result; | |
} | |
// returns the traspose of matrix | |
var transpose = function(matrix) { | |
var result = []; | |
for (var row=0; row < matrix[0].length; row++) { | |
result[row] = []; | |
for (var col=0; col < matrix.length; col++) { | |
result[row][col] = matrix[col][row]; | |
} | |
} | |
return result; | |
} | |
var eratosthenes = function(n) { | |
var mask = new Array(n); | |
var limit = Math.sqrt(n); | |
var result = []; | |
for (var i = 2; i <= limit; i++) { | |
if (!mask[i]) { | |
for (var j = i * i; j <= n; j += i) { | |
mask[j] = true; | |
} | |
} | |
} | |
for (i = 2; i <= n; i++) { | |
mask[i] || result.push(i); | |
} | |
return result; | |
} |
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