259. 3Sum Smaller
class Solution:
def threeSumSmaller(self, nums: List[int], target: int) -> int:
count = 0
nums.sort()
for i in range(len(nums)):
num = nums[i]
left = i + 1
right = len(nums) - 1
while left < right:
threeSum = num + nums[left] + nums[right]
if threeSum < target:
count += right - left
left += 1
else:
right -= 1
return count