func threeSum(_ nums: [Int]) -> [[Int]] {

var result = [[Int]]()

let sortedNums = nums.sorted()

for i in 0..<sortedNums.count - 2 {

if i > 0 && sortedNums[i] == sortedNums[i - 1] {

continue

}

var leftNumber = i + 1

var rightNumber = sortedNums.count - 1

while leftNumber < rightNumber {

let sum = sortedNums[i] + sortedNums[leftNumber] + sortedNums[rightNumber]

if sum < 0 {

leftNumber += 1

} else if sum > 0 {

rightNumber -= 1

} else {

result.append([sortedNums[i], sortedNums[leftNumber], sortedNums[rightNumber]])

while leftNumber < rightNumber && sortedNums[leftNumber] == sortedNums[leftNumber + 1] {

leftNumber += 1

}

while leftNumber < rightNumber && sortedNums[rightNumber] == sortedNums[rightNumber - 1] {

rightNumber -= 1

}

leftNumber += 1

rightNumber -= 1

}

}

}

return result

}