2d方形阵列中的翻转值

Question

有没有办法让我只用一个嵌套for循环执行第一个方法，而没有第一个for循环一些值没有翻转，因为你基本上正在执行逆x，y - - > y，x并翻转x = y（因为0,0是左上角）为什么我的嵌套for循环不能自行工作？

/** 
* <pre> 
* ~~~~~~ BONUS ~~~~~~ EXTRA CREDIT ~~~~~~ 
* transpose grid (similar to arrayReverse) 
* (i.e. reflect over its main diagonal 
* (which runs top-left to bottom-right) 
* you MUST call the swap helper method 
* but you man NOT create a second array for storage 
* example: 
* 1 2 3     1 4 7 
* 4 5 6 would become 2 5 8 
* 7 8 9     3 6 9 
* </pre> 
*/ 
public static void gridTranspose() { 

    if (gridIsSquare() == true) { 
     for (int r = 0; r < grid.length/2 + 1; r++) { 
      gridSwap(0, r, r, 0); 
     } 
     for (int r = 0; r < grid.length/2 + 1; r++) { 
      for (int c = 0; c < grid[0].length; c++) { 
       gridSwap(r, c, c, r); 

      } 

     } 
    } 
} 

/** 
* <pre> 
* ~~~~~~ BONUS ~~~~~~ EXTRA CREDIT ~~~~~~ swap the values at grid[r1][c1] 
* and grid[r2][c2] you may use use an int temp as a temporary variable 
*/ 
public static void gridSwap(int r1, int c1, int r2, int c2) { 
    int temp = grid[r1][c1]; 
    grid[r1][c1] = grid[r2][c2]; 
    grid[r2][c2] = temp; 

} 

Answer 1

下面是代码只做第二循环

public static void gridTranspose() { 
    if (gridIsSquare() == true) { 
     for (int r = 0; r < grid.length/2 + 1; r++) { 
      for (int c = r+1; c < grid[0].length; c++) { 
       gridSwap(r, c, c, r); 

      } 
     } 
    } 
}