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51 lines
1.3 KiB
JavaScript
51 lines
1.3 KiB
JavaScript
/**
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* @details Calculates the number of permutations and combinations.
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* @external_link (Permutation And Combinations)[https://www.geeksforgeeks.org/permutation-and-combination/]
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*/
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/**
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* @brief Calculates the factorial of the given number.
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* @param num: integer
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* @details Factorial of n = n * (n - 1) * (n - 2) * ... * 1
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* @returns integer: Factorial of the number.
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NaN: if negative number is provided.
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*/
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const factorial = (n) => {
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if (n >= 0) {
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if (n === 0) {
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return 1
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} else {
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return n * factorial(n - 1)
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}
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} else {
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return NaN
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}
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}
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/**
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* @brief Calculates the number of Permutations from the given data.
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* @param
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* n: integer -> number of items.
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* r: integer -> number of times n is taken.
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* @returns integer: The number of permutations.
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NaN: if negative number is provided.
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*/
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const permutation = (n, r) => {
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return factorial(n) / factorial(n - r)
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}
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/**
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* @brief Calculates the number of Combinations from the given data.
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* @param
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* n -> number of items.
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* r -> number of times n is taken.
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* @returns integer: The number of combinations.
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NaN: if negative number is provided.
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*/
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const combination = (n, r) => {
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return factorial(n) / (factorial(r) * factorial(n - r))
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}
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// Exports the functions to be used in other files.
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export { factorial, permutation, combination }
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