/**
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* RSS util functions.
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*/
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export default class RSSUtils {
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constructor() { }
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static getRSSvalue(widths, maxWidth, noNarrow) {
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let n = 0;
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for (let width of widths) {
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n += width;
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}
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let val = 0;
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let narrowMask = 0;
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let elements = widths.length;
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for (let bar = 0; bar < elements - 1; bar++) {
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let elmWidth;
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for (elmWidth = 1, narrowMask |= 1 << bar; elmWidth < widths[bar]; elmWidth++, narrowMask &= ~(1 << bar)) {
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let subVal = RSSUtils.combins(n - elmWidth - 1, elements - bar - 2);
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if (noNarrow && (narrowMask === 0) && (n - elmWidth - (elements - bar - 1) >= elements - bar - 1)) {
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subVal -= RSSUtils.combins(n - elmWidth - (elements - bar), elements - bar - 2);
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}
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if (elements - bar - 1 > 1) {
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let lessVal = 0;
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for (let mxwElement = n - elmWidth - (elements - bar - 2); mxwElement > maxWidth; mxwElement--) {
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lessVal += RSSUtils.combins(n - elmWidth - mxwElement - 1, elements - bar - 3);
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}
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subVal -= lessVal * (elements - 1 - bar);
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}
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else if (n - elmWidth > maxWidth) {
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subVal--;
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}
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val += subVal;
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}
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n -= elmWidth;
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}
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return val;
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}
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static combins(n, r) {
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let maxDenom;
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let minDenom;
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if (n - r > r) {
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minDenom = r;
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maxDenom = n - r;
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}
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else {
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minDenom = n - r;
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maxDenom = r;
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}
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let val = 1;
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let j = 1;
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for (let i = n; i > maxDenom; i--) {
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val *= i;
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if (j <= minDenom) {
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val /= j;
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j++;
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}
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}
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while ((j <= minDenom)) {
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val /= j;
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j++;
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}
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return val;
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}
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}
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