Method fourSum

18-4sum/4sum.py:2–26

(self, nums: List[int], target: int)

class Solution:
    def fourSum(self, nums: List[int], target: int) -> List[List[int]]:
        n = len(nums)
        nums.sort()
        ans=[]
        for i in range(n):
            if i>0 and nums[i]==nums[i-1]:
                continue
            for j in range(i+1,n):
                if (j!=i+1 and nums[j]==nums[j-1]):continue
                k = j+1
                l = n-1
                while k<l:
                    sum = nums[i] + nums[j] + nums[k] + nums[l]
                    if sum ==target:
                        li = [nums[i],nums[j],nums[k],nums[l]]
                        ans.append(li)
                        k+=1
                        l-=1
                        while(k<l and nums[k]==nums[k-1]):k+=1
                        while(k<l and nums[l]==nums[l+1]):l-=1
                    elif sum>target:
                        l-=1
                    elif sum<target:
                        k+=1
        return ans