代码随想录算法第一天| 704. 二分查找、27. 移除元素

704. 二分查找

class Solution:
    def search(self, nums: List[int], target: int) -> int: # type: ignore

        ## 左闭右闭写法
        # left, right = 0, len(nums)-1    # 左闭右闭区间，所以right为len(nums) - 1
        # while left <= right:
        #     mid = left + (right - left) // 2  # 防止溢出 等同于(left + right)//2
        #     if nums[mid] > target:
        #         right = mid - 1
        #     elif nums[mid] < target:
        #         left = mid + 1
        #     else:
        #         return mid
        
        # return -1


        ## 左闭右开写法
        left, right = 0, len(nums)  # 左闭右开区间为[left, right), 所以right为len(nums)
        while left < right:
            mid  = left + (right - left) // 2
            if nums[mid] > target:
                right = mid
            elif nums[mid] < target:
                left = mid+1
            else:
                return mid
            
        return -1

27. 移除元素

class Solution:
    def removeElement(self, nums: List[int], val: int) -> int: # type: ignore
        # 双指针解法
        slow = 0
        for fast in range(len(nums)):
            if nums[fast] != val:
                nums[slow] = nums[fast]
                slow += 1

        return slow