问题：
给定一个数组，要求向左或向右循环移动k位
如 1,2,3,4,5,6,7,8,9 向左循环移动移动3位变成4,5,6,7,8,9,1,2,3
答案：
1. 反转数组
reverse(v.begin(), v.begin() + k);
reverse(v.begin() + k, v.end());
reverse(v.begin(), v.end());
2. 最大公约数
int gcd(int m, int n)
{
return n == 0? m : gcd(n, m % n);
}
void rotate(char* data, size_t count, int k)
{
size_t d = gcd(count, k);
for(int i = 0; i < d; i++)
{
size_t cur_pos = i;
size_t prev_pos = cur_pos;
char temp = data[cur_pos];
while((prev_pos = (prev_pos + k) % count ) != i)
{
data[cur_pos] = data[prev_pos];
cur_pos = prev_pos;
}
data[cur_pos] = temp;
}
}
3 模拟STL的rotate
void rotate(char* data, size_t count, int k)
{
int next = k;
int first = 0;
while(first != next)
{
data[first++] == data[next++];
if(next == count)
{
next = k;
}
else if(first == k)
{
k = next;
}
}
}
