题目描述:
给定一个包含 n 个整数的数组 nums 和一个目标值 target,判断 nums 中是否存在四个元素 a,b,c 和 d ,使得 a + b + c + d 的值与 target 相等?找出所有满足条件且不重复的四元组。
注意:
答案中不可以包含重复的四元组。
示例:
给定数组 nums = [1, 0, -1, 0, -2, 2],和 target = 0。
满足要求的四元组集合为:
[
[-1, 0, 0, 1],
[-2, -1, 1, 2],
[-2, 0, 0, 2]
]
解题思路:
class Solution:
def fourSum(self, nums: List[int], target: int) -> List[List[int]]:
nums.sort()
output = []
for x in range(len(nums)):
if x > 0 and nums[x] == nums[x -1]:
continue
for m in range(x+1, len(nums)):
if nums[m] == nums[m -1] and m - 1 != x:
continue
z = len(nums) - 1
for y in range(m+1, len(nums)):
if nums[y] == nums[y -1] and y -1 != m:
continue
four_num = []
while(nums[x] + nums[m] + nums[y] + nums[z] > target and z > y):
z = z - 1
if z == y:
break
if nums[x] + nums[m] + nums[y] + nums[z] == target:
four_num.append(nums[x])
four_num.append(nums[m])
four_num.append(nums[y])
four_num.append(nums[z])
output.append(four_num)
return output
性能分析: