CatalanNumbers.java

packagecom.thealgorithms.maths;

/**
 * Calculate Catalan Numbers
 */
publicfinalclassCatalanNumbers {
privateCatalanNumbers() {
 }

/**
 * Calculate the nth Catalan number using a recursive formula.
 *
 * @param n the index of the Catalan number to compute
 * @return the nth Catalan number
 */
publicstaticlongcatalan(finalintn) {
if (n < 0) {
thrownewIllegalArgumentException("Index must be non-negative");
 }
returnfactorial(2 * n) / (factorial(n + 1) * factorial(n));
 }

/**
 * Calculate the factorial of a number.
 *
 * @param n the number to compute the factorial for
 * @return the factorial of n
 */
privatestaticlongfactorial(finalintn) {
if (n == 0 || n == 1) {
return1;
 }
longresult = 1;
for (inti = 2; i <= n; i++) {
result *= i;
 }
returnresult;
 }
}