java - 生成所有可能的项目组合

Question

我正在制作一个简单的游戏，我想为玩家的负载进行显示，并希望显示他们拥有的所有可能的元素组合。玩家有三个插槽，每个插槽都有各自的枚举(PlayerSlotPosition)。在 Item 枚举中，有多个值，但每个值都需要位于特定的 PlayerSlotPosition 中。

示例:

STICK(PlayerSlotPosition.SLOT_ONE),
STONE(PlayerSlotPosition.SLOT_ONE),
EGG(PlayerSlotPosition.SLOT_TWO),
SHOVEL(PlayerSlotPosition.SLOT_TWO),
PAPER(PlayerSlotPosition.SLOT_THREE),
DIRT(PlayerSlotPosition.SLOT_THREE);

我需要考虑到玩家在任何插槽(或多个插槽)中都没有装备任何元素的可能性，这就是我陷入困境的地方。如果有人有做类似事情的经验并且愿意帮助我，我将非常感激。感谢您的阅读

Answer 1

这里的关键是我想为玩家的负载进行显示，并希望显示他们拥有的所有可能的元素组合。这大大降低了复杂性，因为您所要做的就是打印出库存中元素的可能组合。

public class EnumCombinations {

//Commenting out more than 4 items, loooong printout otherwise
public static enum ITEM{
    STICK(PlayerSlotPosition.SLOT_ONE),
    STONE(PlayerSlotPosition.SLOT_ONE),
    EGG(PlayerSlotPosition.SLOT_TWO),
    SHOVEL(PlayerSlotPosition.SLOT_TWO);
//      PAPER(PlayerSlotPosition.SLOT_THREE),
//      DIRT(PlayerSlotPosition.SLOT_THREE);
    //      DIRT(PlayerSlotPosition.SLOT_THREE);

    private ITEM(PlayerSlotPosition pos){

    }
}

public static enum PlayerSlotPosition{
    SLOT_THREE, SLOT_ONE, SLOT_TWO

}

public static List<List<ITEM>> getItemCombinations(List<ITEM> inventory){
    List<ITEM> prefix = new ArrayList<>();
    List<List<ITEM>> container = new ArrayList<>();
    List<ITEM> remainder; 

    if(inventory==null){
        System.out.println("Printing all item combinations, no inventory");
        remainder =  new ArrayList<>(Arrays.asList(ITEM.values()));
    }

    else {
        remainder = new ArrayList<>(inventory);
    }
    getItemCombinations(prefix, remainder, container);
    return container;
}

private static void getItemCombinations(List<ITEM> prefix, List<ITEM> remainder, List<List<ITEM>> container){
    int n=remainder.size();

    if(remainder.isEmpty()){
        container.add(prefix);
    }

    else {
        for(int i=0; i<n; i++) {
            List<ITEM> r = new ArrayList<>();
            List<ITEM> p = new ArrayList<>(prefix);
            p.add(remainder.get(i));
            for(int j=0; j<remainder.size(); j++){
                if(j==i)
                    continue;
                r.add(remainder.get(j));
            }
            getItemCombinations(p, r, container);
        }
    }
}

public static void main (String[] args) {
    System.out.println(getItemCombinations(null)+"\n");

    List<ITEM> playerINV = new ArrayList<>();
    playerINV.add(ITEM.STICK);
    playerINV.add(ITEM.STONE);
    playerINV.add(ITEM.EGG);
    System.out.println(getItemCombinations(playerINV));

}
}

输出:

Printing all item combinations, no inventory
[[STICK, STONE, EGG, SHOVEL], [STICK, STONE, SHOVEL, EGG], [STICK, EGG, STONE, SHOVEL], [STICK, EGG, SHOVEL, STONE], [STICK, SHOVEL, STONE, EGG], [STICK, SHOVEL, EGG, STONE], [STONE, STICK, EGG, SHOVEL], [STONE, STICK, SHOVEL, EGG], [STONE, EGG, STICK, SHOVEL], [STONE, EGG, SHOVEL, STICK], [STONE, SHOVEL, STICK, EGG], [STONE, SHOVEL, EGG, STICK], [EGG, STICK, STONE, SHOVEL], [EGG, STICK, SHOVEL, STONE], [EGG, STONE, STICK, SHOVEL], [EGG, STONE, SHOVEL, STICK], [EGG, SHOVEL, STICK, STONE], [EGG, SHOVEL, STONE, STICK], [SHOVEL, STICK, STONE, EGG], [SHOVEL, STICK, EGG, STONE], [SHOVEL, STONE, STICK, EGG], [SHOVEL, STONE, EGG, STICK], [SHOVEL, EGG, STICK, STONE], [SHOVEL, EGG, STONE, STICK]]
Printing inventory: 
[[STICK, STONE, EGG], [STICK, EGG, STONE], [STONE, STICK, EGG], [STONE, EGG, STICK], [EGG, STICK, STONE], [EGG, STONE, STICK]]

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