0.2 双指针

[283. 移动零](https://leetcode.cn/problems/move-zeroes/?envType=study-plan-v2&envId=top-100-liked)
```py
class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        not0 = 0
        n = len(nums)
        for i in range(n):
            if nums[i] != 0:
                nums[not0] = nums[i]
                not0 += 1
        for i in range(not0,n):
            nums[i] = 0
```
[11. 盛最多水的容器](https://leetcode.cn/problems/container-with-most-water/?envType=study-plan-v2&envId=top-100-liked)
```py
class Solution:
    def maxArea(self, height: List[int]) -> int:
        n = len(height)
        l, r = 0, n-1
        res = 0
        while l < r:
            h = min(height[l], height[r])
            res = max(res, h * (r-l))
            if height[l] < height[r]:
                l += 1
            else:
                r -= 1
        return res
```
[15. 三数之和](https://leetcode.cn/problems/3sum/?envType=study-plan-v2&envId=top-100-liked)
```py
class Solution:
    def threeSum(self, nums: List[int]) -> List[List[int]]:
        n = len(nums)
        ans = []
        if n < 3:
            return ans
        nums.sort()
        for i in range(n - 2):
            if nums[i] > 0:
                break
            if i > 0 and nums[i] == nums[i - 1]:
                continue
            j, k = i + 1, n - 1
            while j < k:
                s = nums[i] + nums[j] + nums[k]
                if s < 0:
                    j += 1
                    while j < k and nums[j] == nums[j - 1]:
                        j += 1
                elif s > 0:
                    k -= 1
                    while j < k and nums[k] == nums[k + 1]:
                        k -= 1
                else:
                    ans.append([nums[i], nums[j], nums[k]])
                    j += 1
                    k -= 1
                    while j < k and nums[j] == nums[j - 1]:
                        j += 1
                    while j < k and nums[k] == nums[k + 1]:
                        k -= 1
        return ans
```
[42. 接雨水](https://leetcode.cn/problems/trapping-rain-water/?envType=study-plan-v2&envId=top-100-liked)
```py
class Solution:
    def trap(self, height: List[int]) -> int:
        n = len(height)
        l, r = 0, n-1
        m_l, m_r = 0,0
        ans = 0
        while l < r:
            m_l = max(m_l, height[l])
            m_r = max(m_r, height[r])
            ans += (m_l - height[l] + m_r - height[r])
            if height[l] < height[r]:
                l += 1
            else:
                r -= 1
        return ans
```