# Data structure and algorithm surface test questions 80 (26)

Source: Internet
Author: User

6. left rotation string

Title :

Defines the left rotation of a string : moves several characters in front of the string to the end of the string.

If the string abcdef left rotation 2 bit to get the string cdefab. Please implement the function of string left rotation.

The complexity of a string operation that requires time to be n is o (n), and auxiliary memory is O (1).

The first three ABCDEFG will be left-handed. First ABCDEFG->DEFABCG->DEFGBCA (Time is n-3)

Convert the problem to the previous left-hand side of the BCA. First BCA->ACB (time is 1)

Convert the problem to the previous left-hand spin of the CB. CB->BC (Time is 1)

All time complexity is 0 (n).

All problems are the letter 22 Exchange, and the auxiliary memory is O (1).

`#include <iostream>#include<cstring>using namespacestd;Charstr[]="Abcdefghij";voidLeftrotatestring (intLeftintRightintN) {    inttemp=right-Left ;  for(inti=left+n;i<right;i++){        CharC=Str[i]; Str[i]=str[i-N]; Str[i-n]=B; }    //output look at the results     for(intI=0; i<right;i++) cout<<str[i];cout<<Endl; if(temp%n==0)return ; Else{ Left=right-N; N=n-temp%N;    Leftrotatestring (Left,right,n); }}intMain () {intn=7; Leftrotatestring (0, strlen (str), n); return 0;}`

Data structure and algorithm surface test questions 80 (26)

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