反向 2d 数组行

Question

我有二维数组：

int firstDimension = data.length / 8;
int secondDimension = 8;
int[][] arr = new int[firstDimension][secondDimension];

[[1, 1, 1, 1, 1, 1, 1, 1], [0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 1, 1, 1, 1], [1, 0, 1, 0, 1, 0, 1, 0]]
   

我需要反转数组行并获取：

[[1, 0, 1, 0, 1, 0, 1, 0], [0, 0, 0, 0, 1, 1, 1, 1], [0, 0, 0, 0, 0, 0, 0, 0], [1, 1, 1, 1, 1, 1, 1, 1]

我发现算法可以反转1d数组元素：

   for (int i = 0; i < validData.length / 2; i++) {
            int temp = validData[i];
            validData[i] = validData[validData.length - i - 1];
            validData[validData.length - i - 1] = temp;
        }

如何反转数组行？

Answer 1

    int[][] arr = {{1, 1, 1, 1, 1, 1,1, 1}, {0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 1, 1, 1, 1}, {1, 0, 1, 0, 1, 0, 1, 0}};
    
    //assuming all arrays in arr have same length!
    int[][] arr2 = new int [arr.length][arr[0].length];         
    int k = arr2.length-1;
    
    //copy in reverse order
    for (int i = 0; i < arr.length; i++) {          
        for (int j = 0; j < arr[i].length; j++) {
            int temp = arr[i][j];
            arr2[k][j] = temp;
        }
        k--;
    }
    
    //print arr2
    for (int i = 0; i < arr2.length; i++) {
        System.out.print("{");
        for (int j = 0; j < arr2[i].length; j++) {
            System.out.print(arr2[i][j]);
        }
        System.out.print("}");
    }

仅当< code>arr中的所有数组长度相同时，此解决方案才有效