翻转2d方阵列中的值

Question

有没有办法让我只用一个嵌套for循环来做第一个方法，没有第一个for循环，一些值没有翻转，因为你基本上做了逆x，y - ＆gt; y，x和翻转x = y（因为0,0是左上角）为什么单独赢得嵌套for循环工作？

/**
 * <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

以下是仅执行第二个循环的代码

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);

            }
        }
    }
}