Proper divisors: Difference between revisions
→{{header|JavaScript}}
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10: [1, 2, 5]
15120: 79</pre>
=={{header|JavaScript}}==
<lang JavaScript>(function () {
// Proper divisors
function properDivisors(n) {
if (n < 2) return [];
else {
var rRoot = Math.sqrt(n),
intRoot = Math.floor(rRoot),
lows = range(1, intRoot).filter(function (x) {
return (n % x) === 0;
});
return lows.concat(lows.slice(1).map(function (x) {
return n / x;
}).reverse().slice((rRoot === intRoot) | 0));
}
}
// [m..n]
function range(m, n) {
var a = Array(n - m + 1),
i = n + 1;
while (i--) a[i - 1] = i;
return a;
}
var tblOneToTen = [
['Number', 'Proper Divisors', 'Count']
].concat(range(1, 10).map(function (x) {
var ds = properDivisors(x);
return [x, ds.join(', '), ds.length];
})),
dctMostBelow20k = range(1, 20000).reduce(function (a, x) {
var lng = properDivisors(x).length;
return lng > a.divisorCount ? {
n: x,
divisorCount: lng
} : a;
}, {
n: 0,
divisorCount: 0
});
// [[a]] -> bool -> s -> s
function wikiTable(lstRows, blnHeaderRow, strStyle) {
return '{| class="wikitable" ' + (
strStyle ? 'style="' + strStyle + '"' : ''
) + lstRows.map(function (lstRow, iRow) {
var strDelim = ((blnHeaderRow && !iRow) ? '!' : '|');
return '\n|-\n' + strDelim + ' ' + lstRow.map(function (v) {
return typeof v === 'undefined' ? ' ' : v;
}).join(' ' + strDelim + strDelim + ' ');
}).join('') + '\n|}';
}
return wikiTable(
tblOneToTen,
true
) + '\n\nMost proper divisors below 20,000:\n\n ' + JSON.stringify(
dctMostBelow20k
);
})();</lang>
{{out}}
{| class="wikitable"
|-
! Number !! Proper Divisors !! Count
|-
| 1 || || 0
|-
| 2 || 1 || 1
|-
| 3 || 1 || 1
|-
| 4 || 1, 2 || 2
|-
| 5 || 1 || 1
|-
| 6 || 1, 2, 3 || 3
|-
| 7 || 1 || 1
|-
| 8 || 1, 2, 4 || 3
|-
| 9 || 1, 3 || 2
|-
| 10 || 1, 2, 5 || 3
|}
Most proper divisors below 20,000:
{"n":15120,"divisorCount":79}
=={{header|jq}}==
| |||