java - 将 arraylist 发送到数组以检查难题是否可解决

Question

我想发送我的数组列表:

ArrayList<Tile> myList = new ArrayList<Tile>();

之后:

public void shuffleBoard() {
    Collections.shuffle(myList); 

    for (int i = 0; i < SIZE; i++) { 

    }

    switch (SIZE) {

    case 0:
        moveEmptyTile(Direction.UP);

    case 1:
        moveEmptyTile(Direction.DOWN);

    case 2:
        moveEmptyTile(Direction.LEFT);

    case 3:
        moveEmptyTile(Direction.RIGHT);
    }

看起来像这样:

[[ 05 ], [ 12 ], [ ** ], [ 08 ], [ 02 ], [ 03 ], [ 01 ], [ 10 ], [ 04 ], [ 11 ], [ 07 ], [ 15 ], [ 13 ], [ 09 ], [ 06 ], [ 14 ]]

我想将其发送到一个数组，这样我就可以检查棋盘是否可以通过以下代码解决:

 public static boolean isSolvable(int[] state){

    //prepare the mapping from each tile to its position
    int[] positions = new int[16];
    for(int i = 0; i < state.length; i++){
        positions[state[i]] = (i+1)%16;
    }

    //check whether this is an even or odd state
    int row = (positions[0]-1)/4;
    int col = (positions[0]-1)-row*4;
    boolean isEvenState = positions[0] == 0 || row % 2 == col %2;

    //count the even cycles
    int evenCount = 0;
    boolean[] visited = new boolean[16];
    for(int i = 0; i < positions.length; i++){
        if(visited[i]) 
            continue; 
        //a new cycle starts at i. Count its length..
        int cycleLength = 0;
        int nextTile = i;
        while(!visited[nextTile]){
            cycleLength++;
            visited[nextTile] = true;
            nextTile = positions[nextTile];
        }
        if(cycleLength % 2 == 0)
            evenCount++;
    }
    return isEvenState == (evenCount % 2 == 0);

所以我想将我的 Arraylist 转换为 Array，并将其返回为int[] state 到 isSolvable(int[] state) 以便可以检查我的谜题是否可解。

这可能是一些愚蠢的简单的事情，但尝试后我的头很软在本论坛中搜索解决方案。

我的图 block 类:

public class Tile {
private int value;
private static int maxValue = 15;
private static int minValue = 0;


public Tile(int value) {
    setValue(value);

}

public int getValue() {
    return value;
}

public void setValue(int value) {
    if (value <= maxValue)
        this.value = value;
    else if (value > maxValue)
        System.err.print("To high");
}

public boolean isEmpty() {
    if (getValue() == minValue) {
        return true;
    } else {
        return false;
    }
}

@Override
public String toString() {
    if (this.isEmpty() == true)  {
        return "[ ** ]";
    }
    if (this.value < 10) {
        return "[ 0" + value + " ]"; 
    }
    else { 
        return "[ " + value + " ]";
    }
}

}

此致。

Answer 1

一般方法是使用循环构建一个 int 数组，同时将每个 Tile 转换为 int (我猜你想提取 value 字段):

int size = myList.size();
int[] values = new int[size];
for (int i = 0; i < size; i++) {
    values[i] = myList.get(i).getValue();
}

现在您可以像这样简单地调用您的方法:

boolean solveable = isSolvable(values);

使用 Java 8(及更高版本)，您可以使用流简化数组创建代码:

int[] values = myList.stream().mapToInt(Tile::getValue).toArray();