4Sum.py

nums = [1,0,-1,0,-2,2]
target = 0
nums.sort()
res = []
arr = []
def ksum(k, start, target):
    if k != 2:
        for i in range(start, len(nums)-k+1):
            if i > start and nums[i] == nums[i-1]:
                continue
            arr.append(nums[i])
            ksum(k-1, i+1, target- nums[i])
            arr.pop()
        return
    
    # If k = 2 then (TwoSum Method)
    l, r = start, len(nums)-1
    while l < r:
        if nums[l] + nums[r] < target:
            l += 1
        elif nums[l] + nums[r] > target:
            r -= 1
        else:
            res.append(arr + [nums[l], nums[r]])
            l += 1
            while l < r and nums[l] == nums[l-1]:
                l += 1
    
ksum(4, 0, target)
print(res)