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Remove and fix comments
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1 changed files with 8 additions and 30 deletions
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@ -79,42 +79,20 @@ class MathUtil {
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}
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}
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/**
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/**
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* Return a random number given an inclusive range and a set
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* Return a random number given an inclusive range and a number in that
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* of numbers that should be excluded.
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* range that should be excluded.
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* For instance, (1, 5, [2, 3]) will only pick 1, 4, or 5 (with equal
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*
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* For instance, (1, 5, 3) will only pick 1, 2, 4, or 5 (with equal
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* probability)
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* probability)
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*
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*
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* @param {number} lower - The lower bound (inlcusive)
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* @param {number} lower - The lower bound (inlcusive)
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* @param {number} upper - The upper bound (inclusive), such that lower <= upper
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* @param {number} upper - The upper bound (inclusive), such that lower <= upper
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* @param {number} exclude - The numbers to exclude (MUST be in the range)
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* @param {number} exclude - The number to exclude (MUST be in the range)
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*/
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*/
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static inclusiveRandIntWithout(lower, upper, excluded) {
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static inclusiveRandIntWithout(lower, upper, excluded) {
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/**
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// Note that subtraction is the number of items in the
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* By excluding a random integer, we are lowering the number
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// inclusive range [lower, upper] minus 1 already
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* of possible options by one.
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// (e.g. in the set {3, 4, 5}, 5 - 3 = 2)
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*
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* The algorithm is to pick a random integer in the range
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* [lower, upper-1]. If we accidentally pick the exlcuded number,
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* we will instead pikc "upper".
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*
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* So if C is excluded, and we are picking A..F then:
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*
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* A B C D E (no F)
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* = = = = =
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* A B F D E
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*
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* In the event that our excluded number isn't in the range, we will never pick it,
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* and so we don't need to worry about remapping it to something else. For example,
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* if we want to exclude 'F':
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*
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* A B C D E (no F)
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* = = = = =
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* A B C D E
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*/
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// Note that 5 - 3 = 2, but there are 3 options (3, 4, 5).
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// As a result, there isn't a need to subtract 1 as we've
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// already got one less than the size of the range.
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const possibleOptions = upper - lower;
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const possibleOptions = upper - lower;
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const randInt = lower + Math.floor(Math.random() * possibleOptions);
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const randInt = lower + Math.floor(Math.random() * possibleOptions);
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