lc977. Squares of a Sorted Array

977. Squares of a Sorted Array Easy

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Share Given an array of integers A sorted in non-decreasing order, return an array of the squares of each number, also in sorted non-decreasing order.

Example 1:

Input: [-4,-1,0,3,10] Output: [0,1,9,16,100] Example 2:

Input: [-7,-3,2,3,11] Output: [4,9,9,49,121]

Note:

1 <= A.length <= 10000 -10000 <= A[i] <= 10000 A is sorted in non-decreasing order.

思路：找到列表中非负值下标p，q=p-1，然后双指针插入新的列表

代码：python3

class Solution:
    def sortedSquares(self, A: List[int]) -> List[int]:
        p=0
        q=p-1
        for i in range(len(A)):
            if A[i]>=0:
                p=i
                q=i-1
                break
        result=[]
        while p<len(A) and q>=0:
            p2=A[p]*A[p]
            q2=A[q]*A[q]
            if p2>q2:
                result.append(q2)
                q=q-1
            else:
                result.append(p2)
                p=p+1
        if p<len(A):
            while p<len(A):
                result.append(A[p]*A[p])
                p=p+1
        if q>=0:
            while q>=0:
                result.append(A[q]*A[q])
                q=q-1
        return result
if __name__ == '__main__':
    print(Solution().sortedSquares([-7,-3,2,3,11])) 

时间复杂度： O(2m) 空间复杂度：O(m)