3 Sum
Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.
Note: The solution set must not contain duplicate triplets.
For example, given array
S = [-1, 0, 1, 2, -1, -4]
A solution set is:
[ [-1, 0, 1], [-1, -1, 2] ]
def threeSum(nums: Array[Int]):List[(Int,Int,Int)] = {
scala.util.Sorting.quickSort(nums)
var i,j,k,target: Int = 0
j = nums.length - 1
var ret = List[(Int,Int,Int)]()
for (i <- 0 until nums.length) {
k = i + 1
j = nums.length - 1
target = 0 - nums(i)
while (k < j) {
nums(j) + nums(k) match {
case n if n == target => {
ret = Tuple3(nums(i),nums(k),nums(j)) :: ret
while (k < j && nums(k) == nums(k+1)) k += 1
while (k < j && nums(j) == nums(j-1)) j -= 1
j -= 1
k += 1
}
case n if n > target => j -= 1
case n if n < target => k += 1
}
}
}
ret
}
threeSum(Array(0,-1,2,3,4,5,6,1))
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