为什么我的append函数将切片的每个成员更改为要添加的新项目？

Question

I am making a simple prime factor function that can put a slice that is [][]int like

prime_factors_mult(315) => [[3,2],[5,1],[7,1]]

but instead of this result I get [[7,1][7,1][7,1][7,1]] which is afterwards reduced to a empty slice because they repeat them selfs. I tried to look at it with step by step and it changes all the values to the last append. What should I do to avoid this ?

func prime_factors_mult(x []int)(y [][]int){// Problem 36
    in :=[]int{0,0}
    var k [][]int
    for _,item := range x{
        tok := 0
        for i:=0;i<len(x);i++{
            if item == x[i]{
                tok++
            }
        }
        in[0]=item
        in[1]=tok
        k=append(k,in)
    }
    for _,item := range k{
        for i:=0;i<len(k);i++{
            if item[0] != k[i][0]{
                y = append(y,item)
            }
        }
    }
    return
}

Answer 1

You create your in slice once and then modify it each time, so you add the exact same object to k each time.

Append a new slice instead:

k=append(k,[]int{item, tok})