Generate nCr Combinations for a given set

nCr.js

// Author: ChatGPT
function generateCombinations(set, r) {
  const combinations = [];

  function generate(currentCombination, remainingSet, r) {
    if (currentCombination.length === r) {
      combinations.push(currentCombination);
      return;
    }

    if (remainingSet.length < r - currentCombination.length) {
      return;
    }

    for (let i = 0; i < remainingSet.length; i++) {
      // Skip duplicates
      if (i > 0 && remainingSet[i] === remainingSet[i - 1]) {
        continue;
      }

      const newCombination = currentCombination.concat(remainingSet[i]);
      const newSet = remainingSet.slice(i + 1);
      generate(newCombination, newSet, r);
    }
  }

  set.sort(); // Sort the set to ensure duplicates are adjacent
  generate([], set, r);

  return combinations;
}