有人可以向我解释什么是错的吗？ - 按高度排序

Question

I don't know why the code skips some numbers some times. For case 4: a: [4, 2, 9, 11, 2, 16] my output is [2, 4, 2, 9, 11, 16] when the expected output is [2, 2, 4, 9, 11, 16] .

I'm not modifying the index array so it should check every number position's. Also, I'm not sure how line 7 completely works, in position j it's added the elimination of the element i? If so why is there an [0] behind?

I find this code kind of messy but I need to learn from it.

function sortByHeight(a) {
    r = a
    for(i = 0; i < a.length; i++) {
        if (a[i]!= -1) {
            for(j = 0; j < a.length; j++) {
                if (a[j] != -1 && a[i] - a[j] < 0) {
                    r.splice(j,0,r.splice(i,1)[0])
                }
            }
        }
    }
    return r
}

Answer 1

Your mistake is probably thinking that r = a copies the array. That's not the case in JavaScript. JavaScript works by reference, meaning that every value (apart from primitives such as numbers) are actually references. Therefore, r and a point to the exact same array in memory. Modifying one also "modifies the other", so to speak.

You can clone the array by doing one of the following:

r = [ ...a ];
r = a.slice();
r = Array.from(a);

Answer 2

your mistake is in this line (a[j] - a[i] < 0) , you checking it for (a[i] - a[j] < 0) , checking in the reverse order will give you the array in decreasing order, you can reverse the array before returning will give you it in increasing order

function sortByHeight(a) {
r = a
for(i = 0; i < a.length; i++) {
    if (a[i]!= -1) {
        for(j = 0; j < a.length; j++) {
            if (a[j] != -1 && (a[j] - a[i] < 0)) {
                r.splice(j,0,r.splice(i,1)[0])
            }
        }
    }
}
r.reverse()
return r
}