#include<iostream>
using namespace std;
 
/* 後繼 */
int getNext(int i, int m, int n)
{
    return (i%n)*m + i/n;
}
 
/* 前驅 */
int getPre(int i, int m, int n)
{
    return (i%m)*n + i/m;
}
 
/* 處理以下標i為起點的環 */
void movedata(int *mtx, int i, int m, int n)
{
    int temp = mtx[i];  // 暫存
    int cur = i;       // 當前下標
 

    int pre = getPre(cur, m, n);
    while(pre != i)
    {
        mtx[cur] = mtx[pre];
        cur = pre;
        pre = getPre(cur, m, n);
    }
    mtx[cur] = temp;
}
 
/* 轉置，即迴圈處理所有環 */
void transpose(int *mtx, int m, int n)
{
    for(int i=0; i<m*n; ++i)
    {
        int next = getNext(i, m, n);
        while
 
(next > i) // 若存在後繼小於i說明重複
            next = getNext(next, m, n);
        if(next == i)   // 處理當前環 
            movedata(mtx, i, m, n);
    }
}
 
/* 輸出矩陣 */
void print(int *mtx, int m, int n)
{
    for(int i=0; i<m*n; ++i)
    {
        if((i+1)%n == 0)
            cout << mtx[i] << "\n";
        else
 

            cout << mtx[i] << " ";
    }
}
 
/* 測試 */
int main()
{
    int matrix[4*2] = {1,2,3,4,5,6,7,8};
    cout << "Before matrix transposition:" << endl;
    print(matrix, 4, 2);
    transpose(matrix, 4, 2);
    cout << "After matrix transposition:" << endl;
    print(matrix, 2, 4);
    return 0;
}