Java程序对二维数组进行左对角线排序

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对于给定的二维数组，我们的任务是编写一个 Java 程序来对其左对角线上的元素进行排序。对于此问题，我们需要以这样一种方式排列数组的元素，即从左上到右下（即数组的左对角线）读取时，值是有序的。

示例场景

Input: matrix = {3, 8, 2}, {6, 5, 4}, {3, 2, 1};
Output: new_matrix = {1, 4, 2}, {2, 3, 8}, {3, 6, 5}

使用以下排序工具来理解问题

二维数组的左对角线升序排序

这里的想法是找到对角线的长度，它是从起始点开始的剩余行和列的最小值，并创建一个存储对角线元素的数组。然后，我们可以使用 Arrays.sort() 方法对该数组进行排序，以获取按升序排列的对角线元素。

示例

让我们看看实际演示 -

import java.util.Arrays;

public class DgnlSortPrgrm {
   public static void main(String[] args) {
      int[][] twoDArr = {
         {3, 8, 2},
         {6, 5, 4},
         {3, 2, 1}
      };
      System.out.println("Matrix without sorting its diagonal::");
      printMatrix(twoDArr);
      // calling method to sort
      sorting(twoDArr);
      System.out.println("Matrix after sorting its diagonal::");
      printMatrix(twoDArr);
   }
   // method to sort diagonals
   public static void sorting(int[][] twoDArr) {
      int n = twoDArr.length;
      int m = twoDArr[0].length;

      // Sort diagonal that starts from the first row
      for (int col = 0; col < m; col++) {
         sortDgnlElem(twoDArr, 0, col);
      }

      // Sort diagonal that starts from the first column
      for (int row = 1; row < n; row++) {
         sortDgnlElem(twoDArr, row, 0);
      }
   }
   // method to sort elements of the diagonal
   private static void sortDgnlElem(int[][] twoDArr, int row, int col) {
      int n = twoDArr.length;
      int m = twoDArr[0].length;
      int len = Math.min(n - row, m - col);
      int[] dgnl = new int[len];

      // getting diagonal elements
      for (int i = 0; i < len; i++) {
         dgnl[i] = twoDArr[row + i][col + i];
      }

      // sorting diagonal elements
      Arrays.sort(dgnl);

      // sorted elements of the matrix
      for (int i = 0; i < len; i++) {
         twoDArr[row + i][col + i] = dgnl[i];
      }
   }
   // method to print the matrix
   private static void printMatrix(int[][] matrix) {
      for (int[] row : matrix) {
         for (int elem : row) {
            System.out.print(elem + " ");
         }
         System.out.println();
      }
   }
}

运行此代码后，您将获得以下结果 -

Matrix without sorting its diagonal::
3 8 2 
6 5 4 
3 2 1 
Matrix after sorting its diagonal::
1 4 2 
2 3 8 
3 6 5  

二维数组的左对角线降序排序

在这种方法中，我们遵循相同的逻辑，但进行了细微的更改。在这里，我们首先对对角线的元素进行排序，然后反转它们的顺序。

示例

此 Java 程序演示了如何对二维数组的左对角线进行降序排序。

import java.util.Arrays;

public class DgnlSortPrgrm {
   public static void main(String[] args) {
      int[][] twoDArr = {
         {3, 8, 2},
         {6, 5, 4},
         {3, 2, 1}
      };
      System.out.println("Matrix without sorting its diagonal::");
      printMatrix(twoDArr);
      // calling method to sort
      sorting(twoDArr);
      System.out.println("Matrix after sorting its diagonal::");
      printMatrix(twoDArr);
   }
   // method to sort diagonals
   public static void sorting(int[][] twoDArr) {
      int n = twoDArr.length;
      int m = twoDArr[0].length;

      // Sort diagonal that starts from the first row
      for (int col = 0; col < m; col++) {
         sortDgnlElem(twoDArr, 0, col);
      }

      // Sort diagonal that starts from the first column
      for (int row = 1; row < n; row++) {
         sortDgnlElem(twoDArr, row, 0);
      }
   }
   // method to sort elements of the diagonal
   private static void sortDgnlElem(int[][] twoDArr, int row, int col) {
      int n = twoDArr.length;
      int m = twoDArr[0].length;
      int len = Math.min(n - row, m - col);
      int[] dgnl = new int[len];

      // getting diagonal elements
      for (int i = 0; i < len; i++) {
         dgnl[i] = twoDArr[row + i][col + i];
      }

      // sorting diagonal elements
      Arrays.sort(dgnl);

      // reversing the sorted array for descending order
      for (int i = 0; i < len / 2; i++) {
         int temp = dgnl[i];
         dgnl[i] = dgnl[len - i - 1];
         dgnl[len - i - 1] = temp;
      }

      // sorted elements of the matrix
      for (int i = 0; i < len; i++) {
         twoDArr[row + i][col + i] = dgnl[i];
      }
   }
   // method to print the matrix
   private static void printMatrix(int[][] matrix) {
      for (int[] row : matrix) {
         for (int elem : row) {
            System.out.print(elem + " ");
         }
         System.out.println();
      }
   }
}

执行代码后，它将显示以下输出 -

Matrix without sorting its diagonal::
3 8 2 
6 5 4 
3 2 1 
Matrix after sorting its diagonal::
5 8 2 
6 3 4
3 2 1