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ThreeSum.swift
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ThreeSum.swift
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class ThreeSum {
func threeSum(_ nums: [Int]) -> [[Int]] {
var result: [[Int]] = []
let nums = nums.sorted()
let len = nums.count
guard len >= 3 else { return result }
for i in 0..<len {
if i > 0 && nums[i] == nums[i-1] { continue }
let num = 0 - nums[i]
var a = i + 1, b = len - 1
while a < b {
let numA = nums[a], numB = nums[b]
let sum = numA + numB
if sum == num {
result.append([nums[i], numA, numB])
a += 1
b -= 1
while a < b && nums[a] == nums[a-1] { a += 1 }
while a < b && nums[b] == nums[b+1] { b -= 1 }
} else {
sum > num ? b -= 1 : (a += 1)
}
}
}
return result
}
}