Solution for 4 sum problem, has duoTarget optimization for 33% speedup

4_sum.py

class Solution:
    def fourSum(self, nums: List[int], target: int) -> List[List[int]]:
        lenNums = len(nums)
        nums.sort()
        quads = []
        
        for i in range(lenNums - 3):
            if nums[i] == nums[i-1] and i > 0: continue
            for j in range(i + 1, lenNums - 2):
                if nums[j] == nums[j-1] and j > i + 1: continue
                
                k = j + 1
                l = lenNums - 1
                duoTarget = target - nums[i] - nums[j]
                
                while k < l :
                    duoSum = nums[k] + nums[l]
                    if duoSum < duoTarget:
                        k += 1
                    elif duoSum > duoTarget:
                        l -= 1
                    else:
                        quads.append([nums[i], nums[j], nums[k], nums[l]])
                        k += 1
                        while nums[k] == nums[k-1] and k < l: k += 1
        return quads