Question

我正在使用JavaScript来计算出给定玩家列表中羽毛球双打比赛的所有组合。每个玩家都与其他人合作。

EG。如果我有以下球员a，b，c＆amp; d。他们的组合可以是：

a＆amp; b V c＆amp; d

a＆amp; c V b＆amp; d

a＆amp; d V b＆amp; ç

我正在使用下面的代码，我写的是为了完成这项工作，但它效率有点低。它遍历PLAYERS阵列4次，找到每一个组合（包括不可能的组合）。然后它将游戏按字母顺序排序并将其存储在GAMES数组中（如果它尚不存在）。然后我可以使用GAMES数组的前半部分列出所有游戏组合。

麻烦的是，如果我有超过8名玩家，它的运行速度非常慢，因为组合增长是指数级的。

有谁知道我可以使用的更好的方法或算法？我想的越多，我的大脑就越痛！

var PLAYERS = ["a", "b", "c", "d", "e", "f", "g"];
var GAMES = [];

var p1, p2, p3, p4, i1, i2, i3, i4, entry, found, i;
var pos = 0;
var TEAM1 = [];
var TEAM2 = [];

// loop through players 4 times to get all combinations
for (i1 = 0; i1 < PLAYERS.length; i1++)
{
    p1 = PLAYERS[i1];
    for (i2 = 0; i2 < PLAYERS.length; i2++)
    {
        p2 = PLAYERS[i2];
        for (i3 = 0; i3 < PLAYERS.length; i3++)
        {
            p3 = PLAYERS[i3];
            for (i4 = 0; i4 < PLAYERS.length; i4++)
            {
                p4 = PLAYERS[i4];

                if ((p1 != p2 && p1 != p3 && p1 != p4) &&
                   (p2 != p1 && p2 != p3 && p2 != p4) &&
                   (p3 != p1 && p3 != p2 && p3 != p4) &&
                   (p4 != p1 && p4 != p2 && p4 != p3))
                {
                    // sort teams into alphabetical order (so we can compare them easily later)
                    TEAM1[0] = p1;
                    TEAM1[1] = p2;
                    TEAM2[0] = p3;
                    TEAM2[1] = p4;
                    TEAM1.sort();
                    TEAM2.sort();

                    // work out the game and search the array to see if it already exists
                    entry = TEAM1[0] + " & " + TEAM1[1] + " v " + TEAM2[0] + " & " + TEAM2[1];
                    found = false;
                    for (i=0; i < GAMES.length; i++)
                    {
                        if (entry == GAMES[i]) found = true;
                    }

                    // if the game is unique then store it
                    if (!found)
                    {
                        GAMES[pos] = entry;
                        document.write((pos+1) + ": " + GAMES[pos] + "<br>");
                        pos++;
                    }
                }
            }
        }
    }
}

提前致谢。

杰森。

Answer 1

好吧经过一番艰苦的思考后，我想出了这个（见下文）。它仍然没有辉煌，但它更快。

首先我得出结论，我不需要在第一个FOR循环中到达Players数组的末尾，因为那些排列已经解决了。其次，我在第二个FOR循环中增加了起始值，这也是因为那些排列已经解决了。然后我在第3和第4个FOR循环中做了类似的事情。

如果我可以避免长时间的IF比较，那么我可以加快速度！我还添加了名称而不是字符来演示我想要实现的目标。

欢迎任何更多的想法。

var PLAYERS = ["eric", "bob", "jim", "john", "dave", "steve", "fred"];
var GAMES = [];

var p1, p2, p3, p4, i1, i2, i3, i4, entry, found, i;
var pos = 0;
var TEAM1 = [];
var TEAM2 = [];

// loop through players 4 times to get all combinations
for (i1 = 0; i1 < (PLAYERS.length - 1); i1++)
{
    p1 = PLAYERS[i1];
    for (i2 = 1; i2 < PLAYERS.length; i2++)
    {
        p2 = PLAYERS[i2];
        for (i3 = 1; i3 < (PLAYERS.length - 1); i3++)
        {
            p3 = PLAYERS[i3];
            for (i4 = 2; i4 < PLAYERS.length; i4++)
            {
                p4 = PLAYERS[i4];

                if ((p1 != p2 && p1 != p3 && p1 != p4) &&
                   (p2 != p1 && p2 != p3 && p2 != p4) &&
                   (p3 != p1 && p3 != p2 && p3 != p4) &&
                   (p4 != p1 && p4 != p2 && p4 != p3))
                {
                    // sort teams into alphabetical order (so we can compare them easily later)
                    TEAM1[0] = p1;
                    TEAM1[1] = p2;
                    TEAM2[0] = p3;
                    TEAM2[1] = p4;
                    TEAM1.sort();
                    TEAM2.sort();

                    // work out the game and search the array to see if it already exists
                    entry = TEAM1[0] + " & " + TEAM1[1] + " v " + TEAM2[0] + " & " + TEAM2[1];
                    found = false;
                    for (i=0; i < GAMES.length; i++)
                    {
                        if (entry == GAMES[i]) found = true;
                    }

                    // if the game is unique then store it
                    if (!found)
                    {
                        GAMES[pos] = entry;
                        document.write((pos+1) + ": " + GAMES[pos] + "<br>");
                        pos++;
                    }
                }
            }
        }
    }
}

干杯，杰森。

JavaScript优化

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