代码随想录算法公开课day2

复习

704. 二分查找 - 力扣（LeetCode）

class Solution:
    def search(self, nums: List[int], target: int) -> int:
        left = 0
        right = len(nums)
        while right > left:
            if nums[(right+left) // 2] >target:
                right = (right+left) // 2
            elif nums[(right+left) // 2] <target:
                left = (right+left) // 2 + 1
            else:
                return (right+left) // 2
        return -1
            

class Solution:
    def search(self, nums: List[int], target: int) -> int:
        left = 0
        right = len(nums) - 1
        while right >= left:
            if nums[(right+left) // 2] >target:
                right = (right+left) // 2 - 1
            elif nums[(right+left) // 2] <target:
                left = (right+left) // 2 + 1
            else:
                return (right+left) // 2
        return -1
            

27. 移除元素 - 力扣（LeetCode）

class Solution:
    def removeElement(self, nums: List[int], val: int) -> int:
        low = 0
        for fast in range(len(nums)):
            if nums[fast] != val:
                nums[low] = nums[fast]
                low += 1
        return low

977. 有序数组的平方 - 力扣（LeetCode）

class Solution:
    def sortedSquares(self, nums: List[int]) -> List[int]:
        left = 0
        right = len(nums) - 1
        index = right
        result = [0] * len(nums)
        count = 0
        while left <= right:
            if nums[left] ** 2 <= nums[right] ** 2:
                result[index] =  nums[right] ** 2
                right -= 1
            else:
                result[index] =  nums[left] ** 2
                left += 1
            index -= 1
        return result

209. 长度最小的子数组 - 力扣（LeetCode）

class Solution:
    def minSubArrayLen(self, target: int, nums: List[int]) -> int:
        left = 0
        right = 0
        lenth = len(nums)
        result = len(nums) + 1
        value = 0
        while right < lenth:
            value += nums[right]
            while value >= target:
                result = min(result,right - left + 1)
                value -= nums[left]
                left+=1
            right += 1
        if result != len(nums) + 1:
            return result
        return 0

59. 螺旋矩阵 II - 力扣（LeetCode）

class Solution:
    def generateMatrix(self, n: int) -> List[List[int]]:
        loop = n // 2
        mid = n // 2
        startx = 0
        starty = 0
        count = 1
        result = [[0]*n for _ in range(n)]
        for r in range(1,loop+1):
            for j in range(startx,n - r):
                result[startx][j] = count
                count += 1
            for j in range(starty,n-r):
                result[j][n-r] = count
                count += 1
            for j in range(n-r,startx,-1):
                result[n-r][j] = count
                count += 1
            for j in range(n-r,starty,-1):
                result[j][starty] = count
                count += 1
            startx += 1
            starty += 1
        if n % 2 != 0:
            result[mid][mid] = count
        return result

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