molstar
Version:
A comprehensive macromolecular library.
61 lines • 1.92 kB
JavaScript
"use strict";
/**
* Copyright (c) 2018-2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
*
* @author Alexander Rose <alexander.rose@weirdbyte.de>
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.combinations = exports.CombinationIterator = void 0;
function P(m, n) {
var p = 1;
while (n--)
p *= m--;
return p;
}
function C(m, n) {
if (n > m)
return 0;
return P(m, n) / P(n, n);
}
function nextIndex(n) {
var smallest = n & -n;
var ripple = n + smallest;
var newSmallest = ripple & -ripple;
var ones = ((newSmallest / smallest) >> 1) - 1;
return ripple | ones;
}
;
var CombinationIterator = /** @class */ (function () {
function CombinationIterator(array, count) {
this.array = array;
this.hasNext = false;
this.index = (1 << count) - 1;
this.size = C(array.length, count);
this.maxIndex = 1 << array.length,
this.value = new Array(count);
this.hasNext = count > 0 && count <= array.length;
}
CombinationIterator.prototype.move = function () {
if (this.hasNext) {
var i = 0, j = 0, n = this.index;
for (; n; n >>>= 1, i++) {
if (n & 1)
this.value[j++] = this.array[i];
}
this.index = nextIndex(this.index);
this.hasNext = this.index < this.maxIndex;
}
return this.value;
};
return CombinationIterator;
}());
exports.CombinationIterator = CombinationIterator;
function combinations(array, count) {
var out = [];
var combinationIt = new CombinationIterator(array, count);
while (combinationIt.hasNext)
out.push(combinationIt.move().slice());
return out;
}
exports.combinations = combinations;
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