数据结构与算法_sec01_数组

1、二分查找：

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

nums = [1,3,5,6,7,9,12]
target = 3
a = Solution().search(nums,target)
print(a)

2、使用双指针法移除元素

class Solution:
    def remove(self,nums,val):
        fast = slow = 0
        while fast < len(nums):
            if nums[fast] != val:
                nums[slow] = nums[fast]
                slow += 1
            fast += 1
        return slow

nums = [1,3,5,3,7,9,12]
target = 3
a = Solution().remove(nums,target)
print(a)

3、有序数组的平方：

class Solution:
    def sortedSquares(self, nums):
        for i in range(len(nums)):
            nums[i] = nums[i]**2
        nums.sort()
        return nums
nums = [-1,3,-5,7,9,12]

a = Solution().sortedSquares(nums)
print(a)

#使用双指针法
class Solution:
    def sortedSquares(self, nums):
        n = len(nums)
        i = 0
        j = n-1
        k = n-1
        ans = [-1]*n
        print(ans)
        while i <= j:
            lm = nums[i]**2
            rm = nums[j]**2
            if lm > rm:
                ans[k] = lm
                i += 1
            else:
                ans[k] = rm
                j -= 1
            k -= 1
        return ans

nums = [-1,3,-5,7,9,12]

a = Solution().sortedSquares(nums)
print(a)

4、长度最小的子数组：

class Solution:
    def minSubArrayLen(self, nums, target):
        if not nums:
            return 0
        n = len(nums)
        ans = n + 1
        start = 0
        end = 0
        sum = 0

        while end < n:
            sum += nums[end]
            while sum >= target:
                ans = min(ans, end - start + 1)
                sum -= nums[start]
                start += 1
            end += 1
        return 0 if ans == n+1 else ans

nums = [2,3,1,2,4,3]

a = Solution().minSubArrayLen(nums,7)
print(a)

5、螺旋矩阵

class Solution:
    def generateMatrix(self, n):
        matrix = [[0]*n for _ in range(n)]
        #空矩阵表示方法
        print(matrix)
        left, right, up, down = 0, n-1, 0, n-1
        number = 1

        while left < right and up < down:

            for x in range(left, right):
                matrix[up][x] = number
                number += 1

            for y in range(up, down):
                matrix[y][right] = number
                number += 1

            for x in range(right, left, -1):
                matrix[down][x] = number
                number += 1

            for y in range(down, up, -1):
                matrix[y][left] = number
                number += 1

            left += 1
            right -= 1
            up += 1
            down -= 1
        if n % 2:
            matrix[n//2][n//2] = number

        return matrix

a = Solution().generateMatrix(4)
print(a)