在JavaScript中将Pronumerals一起添加 [英] Adding Pronumerals together in javascript

问题描述

我希望javascript能够解释以下内容(a和b总是会有所不同，因此这些只是一个示例)

I want javascript to be able to interpret the following (a and b are always going to be different, so these are just an example)

a=(3x)+y  
b=x+(4y)  

并返回以下内容

a+b=(4x)+(5y)  

所有变量都是字符串，而不是整数，因此不能将数学应用于a，b，x或y

all variables are strings and not integers so math can not be applied to a,b,x or y

由于我不知道从哪里开始，所以我没有在这个特定实例上开始.

I have not started on this particular instance, due to the fact that i don't know where to start.

P.S.我没有使用jQuery的任何经验，因此，如果可能，请尝试并避免使用它

P.S. I have not had any experience with jQuery, so if possible, try and avoid it

该程序旨在帮助在游戏《我的世界》中查找原材料.例如，如果您要使用钻石剑(a)和钻石镐(b)，则a需要1颗木头(x)和2颗钻石(y)，而b需要1颗木头(x)和3个菱形(y).一旦我通过该程序运行它，我想回应一下，它需要2颗木材和5颗钻石.对不起，之前有任何疑问...

The program is designed to help find raw materials in the game minecraft. For example if you want a diamond sword (a) and a diamond pickaxe (b), a requires 1 wood (x) and 2 diamonds (y), and b requires 1 wood (x) and 3 diamonds (y). Once i run it through this program, i would like a response saying that it requires 2 wood and 5 diamonds. Sorry for any prior confusion...

推荐答案

首先，让我们编写三个小辅助函数:

First, let's program three little helper functions:

// exprToDict("3x + y") -> {x:3, y:1}
function exprToDict(e) {
    var d = {};
    e.replace(/(\d+)\s*(\w+)|(\w+)/g, function($0, $1, $2, $3) {
        d[$2 || $3] = parseInt($1 || 1);
    });
    return d;
}

// addDicts({x:1, y:2}, {x:100, y:3}) -> {x:101, y:5}
function addDicts(a, b) {
    var d = {};
    for(var x in a) d[x] = a[x];
    for(var x in b) d[x] = (d[x] || 0) + b[x];
    return d;
}

// dictToExpr({x:1, y:2}) -> x + (2 y)
function dictToExpr(d) {
    var e = [];
    for(var x in d)
        if(d[x] == 1)
            e.push(x);
        else
            e.push("(" + d[x] + " " + x + ")");
    return e.join(" + ")
}

一旦知道了，就可以编写主要功能了:

Once we've got that, we're ready to code the main function:

function addThings(a, b) {
    return dictToExpr(
        addDicts(
            exprToDict(a),
            exprToDict(b)
    ))
}

让我们对其进行测试:

sword = "(3 wood) + diamond"
pickaxe = "wood + (2 diamond)"

console.log(addThings(sword, pickaxe))

结果:

(4 wood) + (3 diamond)

为了处理两个以上的事情，请修改addDicts以接受数组:

In order to process more than two things, modify addDicts to accept arrays:

function addDicts(dicts) {
    var sum = {};
    dicts.forEach(function(d) {
        for(var x in d)
            sum[x] = (sum[x] || 0) + d[x];
    });
    return sum;
}

并将addThings重写为:

function addThings(things) {
    return dictToExpr(
        addDicts(
            things.map(exprToDict)));
}

示例:

sword = "(3 wood) + diamond"
pickaxe = "wood + (2 diamond)"
house = "10 wood + iron"


console.log(addThings([sword, pickaxe, house]))

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