How to embed and override a struct in Go - go

Question

I am constructing the min/max heaps of ints to satisfy the interface from container/heap.
The min heap works well such as
type MinHeapInt []int
func (h MinHeapInt) Len() int {
return len(h)
}
func (h MinHeapInt) Less(i, j int) bool {
return h[i] < h[j]
}
func (h MinHeapInt) Swap(i, j int) {
h[i], h[j] = h[j], h[i]
}
func (h *MinHeapInt) Peek() interface{} {
return (*h)[0]
}
func (h *MinHeapInt) Push(x interface{}) {
*h = append(*h, x.(int))
}
func (h *MinHeapInt) Pop() interface{} {
length := len(*h)
res := (*h)[length - 1]
*h = (*h)[0 : length - 1]
return res
}
Now I am trying to develop the max heap by only overriding the Less method.
The first solution does not work since it cannot find the array
type MaxHeapInt struct {
MinHeapInt
}
func (h MaxHeapInt) Less(i, j int) bool {
return h[i] > h[j]
}
The second solution only keeps the Less method.
type MaxHeapInt MinHeapInt
func (h MaxHeapInt) Less(i, j int) bool {
return h[i] > h[j]
}
Wonder if there is anyway to get around. Thanks!

Answer 1

Your first solution is trying to index the MaxHeapInt struct, not the MinHeapInt slice.
type MaxHeapInt struct {
MinHeapInt
}
func (h MaxHeapInt) Less(i, j int) bool {
return h.MinHeapInt[i] > h.MinHeapInt[j]
}
If you want them to be initialized the same, then create a partial heap implementation, and wrap in the desired struct (similar to the wrapper example in the sort package).
type Max struct{ IntHeap }
func (h Max) Less(i, j int) bool {
return h.IntHeap[i] > h.IntHeap[j]
}
type Min struct{ IntHeap }
func (h Min) Less(i, j int) bool {
return h.IntHeap[i] < h.IntHeap[j]
}
type IntHeap []int
func (h IntHeap) Len() int { return len(h) }
func (h IntHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
func (h *IntHeap) Peek() interface{} { return (*h)[0] }
func (h *IntHeap) Push(x interface{}) {
*h = append(*h, x.(int))
}
func (h *IntHeap) Pop() interface{} {
length := len(*h)
res := (*h)[length-1]
*h = (*h)[0 : length-1]
return res
}
// Now these can be initialized like
// Min{IntHeap{1, 2, 3}}
// Max{IntHeap{1, 2, 3}}