LC 3. 3Sum

function threeSum(nums: number[]): number[][] {
  nums = nums.sort((a, b) => a - b)
  let answer = []
  for (let i = 0; i < nums.length - 2; i++) {
    if (i > 0 && nums[i] === nums[i - 1]) {
      continue
    }
    let leftPointer = i + 1
    let rightPointer = nums.length - 1
    while (leftPointer < rightPointer) {
      let sum = nums[leftPointer] + nums[i] + nums[rightPointer]
      if (sum === 0) {
        answer.push([nums[i], nums[leftPointer], nums[rightPointer]])

        while (leftPointer < rightPointer && nums[leftPointer] === nums[leftPointer + 1]) {
          leftPointer++
        }

        while (leftPointer < rightPointer && nums[rightPointer] === nums[rightPointer - 1]) {
          rightPointer--
        }

        leftPointer++
        rightPointer--
      } else if (sum > 0) {
        rightPointer--
      } else if (sum < 0) {
        leftPointer++
      }
    }
  }

  return answer
}