字符串的旋转

题目：给定一个字符串，要求将字符串前面的若干个字符移动字符串的尾部。例如，将字符串"abcdef"的前3个字符'a','b'和'c'移到字符串的尾部，那么原字符串将变成"defabc"。请实现此功能。（编程之美1.1）

#include<iostream>
using namespace std;


#define MAX 1000
typedef char ElemType;


typedef struct LNode
{
ElemType data;
struct LNode *next;
}SqList;




void CreateList(SqList *&L,ElemType a[])
{
L = (SqList *)malloc(sizeof(SqList));
SqList *p;
SqList *r = L;
int i = 0;
while (a[i] != '\0')
{   
p = (SqList *)malloc(sizeof(SqList));
p->data = a[i];
r->next = p;
r = p;
i++;
}
r->next = NULL;
}


void DispList(SqList *L)
{
SqList *p = L->next;
while (p!=NULL)
{
cout << p->data;
p = p->next;
}
cout << endl;
}


void DestroyList(SqList *&L)
{
SqList *pre = L, *p = L->next;
while (p != NULL)
{
free(pre);
pre = p;
p = pre->next;
}
free(pre);
}
int ListLength(SqList *&L)
{
int j = 0;
SqList *p = L->next;
while (p != NULL)
{
j++;
p = p->next;
}
return j;
}


SqList *SubList(SqList *L, int i, int j)
{
int k;
SqList *str, *p = L->next, *q, *r;
str = (SqList *)malloc(sizeof(SqList));
str->next = NULL;
r = str;
if (i <= 0 || i > ListLength(L) || j<0 || i + j -1>ListLength(L))
return str;
for (k = 0; k < i - 1; k++)
p = p->next;
for (k = 1; k <= j; k++)
{
q = (SqList *)malloc(sizeof(SqList));
q->data = p->data;
r->next = q;
r = q;
p = p->next;
}
r->next = NULL;
return str;
}
SqList *ConCatList(SqList *s1, SqList *s2)
{
SqList *str, *p = s1->next, *q,*r;
str = (SqList *)malloc(sizeof(SqList));
r = str;
while (p != NULL)
{
q = (SqList *)malloc(sizeof(SqList));
q->data = p->data;
r->next = p;
r = p;
p = p->next;
}
p = s2->next;
while (p != NULL)
{
q = (SqList *)malloc(sizeof(SqList));
q->data = p->data;
r->next = q;
r = q;
p = p->next;
}
r->next = NULL;
return str;
}


SqList *DiviList(SqList *&L, int i)
{
int j = ListLength(L);
SqList *s1, *s2, *str;
s1 = SubList(L, 1, 3);
s2 = SubList(L, i+1, 3);
str = ConCatList(s2, s1);


return str;
}
int main(void)
{   
cout << "please enter the strings: " << endl;


char *s = new char[MAX];
cin >> s;
SqList *L, *s1;
CreateList(L, s);
DispList(L);
cout << ListLength(L) << endl;
s1 = DiviList(L, 3);
DispList(s1);
DestroyList(L);


return 0;
}