如何按列对2D整数数组排序 [英] How to sort a 2D integer array by columns

问题描述

如果我们有一个二维int数组，如下所示:

If we have a 2D int array that looks like this:

6 | 8 | 9 | 16 
0 | 6 |-3 | 4
18| 2 | 1 | 11

超出预期的输出将是:

 0 | 2 |-3 | 4 
 6 | 6 | 1 | 11
 18| 8 | 9 | 16

当我想到如何垂直排序时，我会阻止.

I block when when i think of it how to sort vertically.

int[][] array = new int[10][10]; 
for(int i = 0; i < array.length; i++){
    for(int j = 0; j < array[0]; j++){
       //here i block because i don't know how i would vertically sort them
    }
}

我知道有很多与此相关的主题，而在所有主题中，没有一个主题对我有用.因此，我为这篇文章表示歉意，但我被困住了.

I know there are a lot of topics about this and in all of them not one of them worked for me. Therefore I apologize for this post but I am stuck.

推荐答案

了解线性代数请:

带有矩阵转置

public class MatrixSort {

    private static final int MATRIX[][] = { 
              { 6, 8, 9, 16 }, 
              { 0, 6, -3, 4 }, 
              { 18, 2, 1, 11 } 
     };

    private static int[][] transpose(int[][] m) {
        int[][] ret = new int[m[0].length][m.length];
        for (int i = 0; i < m.length; i++)
            for (int j = 0; j < m[0].length; j++)
                ret[j][i] = m[i][j];
        return ret;
    }

    public static void main(String[] args) {
        int ret[][] = transpose(MATRIX);
        for(int i=0; i < ret.length; i++) {
            Arrays.sort(ret[i]);
        }
        ret = transpose(ret);
        for(int i=0; i < ret.length; i++) {
            for(int j=0; j < ret[i].length; j++) {
                System.out.print(ret[i][j]);
                System.out.print(" | ");
            }
            System.out.print('\n');
        }
    }

}

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