three_sum.js

function threeSum(nums) {
  const res = []
  nums.sort()
  for (let i = 0; i < nums.length - 2; i++) {
    if (i > 0 && nums[i] === nums[i - 1]) {
      continue
    }
    let l = i + 1
    let r = nums.length - 1
    while (l < r) {
      const s = nums[i] + nums[l] + nums[r]
      if (s > 0) {
        r -= 1
      } else if (s < 0) {
        l += 1
      } else {
        res.push([nums[i], nums[l], nums[r]])
        while (l < r && nums[l] === nums[l + 1]) {
          l++
        }
        while (l < r && nums[r] === nums[r - 1]) {
          r -= 1
        }
        l++
        r--
      }
    }
  }
  return res
}

const x = [-1, 0, 1, 2, -1, -4]
console.log('input: ', x)
console.log('output should be: ', [[-1, -1, 2], [-1, 0, 1]])
console.log('output: ', threeSum(x))