NC110 数组循环右移

额外空间

多次逆序

环型替换

class Solution {
public:
    vector<int> solve(int n, int m, vector<int>& a) {
        m = m % n;      // 循环右移n位数组元素不变
        if(m == 0){
            return a;
        }
        int swap_count=0;
        int i=0, tmp, old_tmp;
        while(swap_count < n){
            int prev = i, next;
            tmp = a[prev];
            old_tmp = tmp;
            do{
                next = (prev + m) % n;
                tmp = a[next];
                a[next] = old_tmp;
                prev = next;
                old_tmp = tmp;
                swap_count ++;
            }while(next != i);
            i++;
        }
        return a;
    }
};