題目:

Write a function that reverses a string. The input string is given as an array of characters s.

You must do this by modifying the input array in-place with O(1) extra memory.

給定一個由字元組成的陣列,將其反轉
題目限制我們的空間複雜度只能是O(1)

這題用簡單的two pointer就能解決

class Solution:
    def reverseString(self, s: List[str]) -> None:
        """
        Do not return anything, modify s in-place instead.
        """
        l=0
        r=len(s)-1
        while l<r:
            temp=s[l]
            s[l]=s[r]
            s[r]=temp
            l=l+1
            r=r-1

設立兩個指標(l,r),一個從陣列頭,一個從陣列尾開始走
路上不斷交換值直到兩者相遇或交錯
我們就成功反轉該陣列了
最後執行時間197ms(faster than 98.06%)

那我們下題見