如何在Java选择排序（Selection Sort）中显示每轮排序过程

Here's the modified code that prints each pass of the sorting process, along with key explanations:

import java.util.Scanner;

public class SelectionSortWithPasses {
    public static void main(String[] args) {
        Scanner ss = new Scanner(System.in);
        int a, j, temp;
        int arr[] = new int[50];

        // Input number of elements
        System.out.print("Input a number: ");
        int num = ss.nextInt();
        System.out.println();

        // Input array elements
        for (a = 0; a < num; a++) {
            System.out.print("a[" + a + "]: ");
            arr[a] = ss.nextInt();
        }

        // Print unsorted array
        System.out.print("\nUnSorted Array: ");
        printArray(arr, num);

        // Selection sort with pass printing
        for (a = 0; a < num; a++) {
            // Inner loop to compare and swap elements (your original logic)
            for (j = a + 1; j < num; j++) {
                if (arr[a] > arr[j]) {
                    temp = arr[a];
                    arr[a] = arr[j];
                    arr[j] = temp;
                }
            }
            // Print current pass state
            int passNumber = a + 1;
            System.out.print(passNumber + getOrdinalSuffix(passNumber) + " Pass: ");
            printArray(arr, num);
        }

        // Print sorted array
        System.out.print("Sorted Array Values :");
        printArray(arr, num);

        ss.close();
    }

    // Helper method to print array elements (avoids code duplication)
    private static void printArray(int[] arr, int length) {
        for (int i = 0; i < length; i++) {
            System.out.print(arr[i] + "  ");
        }
        System.out.println();
    }

    // Helper method to generate ordinal suffixes (1st, 2nd, 3rd, etc.)
    private static String getOrdinalSuffix(int number) {
        if (number >= 11 && number <= 13) {
            return "th";
        }
        switch (number % 10) {
            case 1: return "st";
            case 2: return "nd";
            case 3: return "rd";
            default: return "th";
        }
    }
}

Key Changes: #

1. Added Helper Methods:

   • printArray: Reusable function to print array elements, used for unsorted, pass-by-pass, and sorted output.
   • getOrdinalSuffix: Generates correct suffixes for pass numbers to match your expected format.

2. Pass-by-Pass Printing:

   • After each iteration of the outer sorting loop, we print the current state of the array with the appropriate 1-based pass label.

3. Formatting & Cleanup:

   • Added newlines to match the spacing in your expected output.
   • Closed the Scanner to prevent resource leaks.

Optional: Standard Selection Sort #

Your current code swaps elements immediately when a smaller value is found. For the standard selection sort (find the minimum element first, then swap once per pass), replace the sorting loop with this code:

for (a = 0; a < num - 1; a++) {
    int minIndex = a;
    // Find index of the smallest element in the unsorted portion
    for (j = a + 1; j < num; j++) {
        if (arr[j] < arr[minIndex]) {
            minIndex = j;
        }
    }
    // Swap only if a smaller element was found
    if (minIndex != a) {
        temp = arr[a];
        arr[a] = arr[minIndex];
        arr[minIndex] = temp;
    }
    // Print current pass
    int passNumber = a + 1;
    System.out.print(passNumber + getOrdinalSuffix(passNumber) + " Pass: ");
    printArray(arr, num);
}

内容的提问来源于stack exchange，提问作者Ellie Riggs