题目：原题链接（中等）
标签：数组、双指针
解法 | 时间复杂度 | 空间复杂度 | 执行用时 |
Ans 1 (Python) | O ( N 3 ) | O ( 1 ) | 2376ms (13.76%) |
Ans 2 (Python) | O ( N 2 ) | O ( N ) | 100ms (94.18%) |
Ans 3 (Python) |
解法一：
class Solution:
def threeSumSmaller(self, nums: List[int], target: int) -> int:
size = len(nums)
ans = 0
for i in range(size):
for j in range(i + 1, size):
for k in range(j + 1, size):
if nums[i] + nums[j] + nums[k] < target:
ans += 1
return ans解法二：
class Solution:
def threeSumSmaller(self, nums: List[int], target: int) -> int:
nums.sort()
size = len(nums)
ans = 0
for i in range(size - 2):
l, r = i + 1, size - 1
aim = target - nums[i]
while l < r:
if nums[l] + nums[r] >= aim:
r -= 1
else:
ans += r - l
l += 1
return ans
