在不重复的情况下成对获取数组元素的所有可能组合

function getCombinations(nums) {
  const result = [];

  function backtrack(selected, remaining) {
    if (remaining.length === 0) {
      result.push(selected.slice());
      return;
    }

    for (let i = 0; i < remaining.length; i++) {
      const num = remaining[i];
      selected.push(num);
      remaining.splice(i, 1);

      backtrack(selected, remaining);

      remaining.splice(i, 0, num);
      selected.pop();
    }
  }

  backtrack([], nums);
  return result;
}

const nums = [1, 2, 3];
const combinations = getCombinations(nums);
console.log(combinations);