java - 使用数组列表进行选择排序？

Question

我必须适应学校的选择排序。目的是返回玩家的排名，获胜者在前，等等。排名相同的玩家应按照他们在锦标赛列表中出现的顺序列出。

public ArrayList<Player> ranking() {
    ArrayList<Player> result = new ArrayList<Player>();
    // Supply this code!
    return result;

现在这是我调整选择排序的尝试

    int smallInt = 0;
    int j=0;
    int smallIntIndex = 0;      

    for(int i=1;i<players.size();i++){
        smallInt = result.get(i-1).totalScore();
        smallIntIndex = i-1;
        for(j=i;j<players.size();j++){
            if(result.get(j).totalScore()<smallInt){
                smallInt = result.get(j).totalScore();
                smallIntIndex = j;                    
            }
        }
        int temp = result.get(smallIntIndex).totalScore();
        result.set(smallIntIndex, result.get(i-1));
        result.set(i-1, temp);
    }
    return result;

唯一给我错误的是最后一行

result.set(i-1, temp); //The method set(int, Player) in the type 
                       //ArrayList<Player> is not applicable for the arguments (int, int)

知道我做错了什么吗？大部分的适应都是正确的吗？感谢任何帮助。谢谢

附:请不要建议比较器或类似的东西，这不是我想要的。

Answer 1

有几件事:

• 您正在初始化一个空的 result 数组，但该算法通过交换元素对现有数组起作用。您必须使用 players

  的值初始化 result

  List<Player> result = new ArrayList<Player>(players);
  

• 变量 temp 类型必须是 Player 而不是 int

  Player temp = result.get(smallIntIndex);
  

• 外循环必须从索引 0 开始，不能1

• 外层循环必须以players.size() - 1结束
• 内部循环必须从索引i+1开始
• 每次在外循环中都交换元素，这是不正确的。仅当找到新的最小值时才交换它们

更正后的代码:

public ArrayList<Player> ranking() {
    List<Player> result = new ArrayList<Player>(players);
    int smallInt = 0;
    int j=0;
    int smallIntIndex = 0;      

    for(int i=0;i<result.size() - 1;i++){
        smallInt = result.get(i).totalScore();
        smallIntIndex = i;
        for(j=i+1;j<result.size();j++){
            if(result.get(j).totalScore()<smallInt){
                smallInt = result.get(j).totalScore();
                smallIntIndex = j;                    
            }
        }

        if (i != smallIntIndex) {
            Player temp = result.get(smallIntIndex);
            result.set(smallIntIndex, result.get(i));
            result.set(i, temp);
        }
    }
    return result;
}

编辑:您要求排序后的结果必须进入一个单独的results数组，该数组最初是空的。这是一种方法:

public ArrayList<Player> ranking() {
    List<Player> result = new ArrayList<Player>();
    int smallInt = 0;
    int j=0;
    int smallIntIndex = 0;      

    for(int i=0;i<players.size() - 1;i++){
        smallInt = players.get(i).totalScore();
        smallIntIndex = i;
        for(j=i+1;j<players.size();j++){
            if(players.get(j).totalScore()<smallInt){
                smallInt = players.get(j).totalScore();
                smallIntIndex = j;                    
            }
        }

        if (i != smallIntIndex) {
            Player player = players.get(smallIntIndex);

            result.add(player);
            players.set(smallIntIndex, players.get(i));
        }
    }
    return result;
}

引用:Wikipedia's article on selection sort