Nine-chapter algorithm surface question 55 rotating string

Nine Chapters count judges Net-original website

http://www.jiuzhang.com/problem/55/

Topics

Offsets a string and a rotated offset, and shifts the string to the right offset bit.

For example: "ABCDEFG" Loop shifted right 4 bit after changed to: "DEFGABC"

Requires an O (1) extra space cost, O (n) time

Online testhttp://lintcode.com/problem/rotate-string/

Answer

The three-step inversion method is used.

Take s= "ABCDEFG" offset=4 as an example

First, the string is considered: "abc" + "DEFG"

First overall reversal: Get "gfed" + "CBA"

Then each reversal: Get "DEFG" + "abc" = "Defgabc"

Time complexity O (n), additional space complexity O (1)

Nine-chapter algorithm surface question 55 rotating string