We have a collection of stones, each stone has a positive integer weight.

Each turn, we choose the two heaviest stones and smash them together.  Suppose the stones have weights `x` and `y` with `x <= y`.  The result of this smash is:

• If `x == y`, both stones are totally destroyed;
• If `x != y`, the stone of weight `x` is totally destroyed, and the stone of weight `y` has new weight `y-x`.

At the end, there is at most 1 stone left.  Return the weight of this stone (or 0 if there are no stones left.)

``````Example 1:

Input: [2,7,4,1,8,1]
Output: 1
Explanation:
We combine 7 and 8 to get 1 so the array converts to [2,4,1,1,1] then,
we combine 2 and 4 to get 2 so the array converts to [2,1,1,1] then,
we combine 2 and 1 to get 1 so the array converts to [1,1,1] then,
we combine 1 and 1 to get 0 so the array converts to  then that's the value of last stone.
``````

Solution:

``````import "container/heap"

type IntHeap []int

func (h IntHeap) Len() int {return len(h)}
func (h IntHeap) Less(x, y int) bool {return  h[x] > h[y]}
func (h IntHeap) Swap(x, y int) {h[x], h[y] = h[y], h[x]}
func (h *IntHeap) Push(x  interface{}) {
*h = append(*h, x.(int))
}
func (h *IntHeap) Pop() interface{} {
if len(*h) == 0 {
return 0
}
old := *h
x := old[len(old) - 1]
*h = old[0: len(old) - 1]
return x
}

func lastStoneWeight(stones []int) int {
h := &IntHeap{}
heap.Init(h) //important
for i := 0; i < len(stones); i++ {
heap.Push(h, stones[i])
}
for len(*h) >= 2 {
a := (heap.Pop(h)).(int)
b := (heap.Pop(h)).(int)
if b > a{
b, a = a, b
}
heap.Push(h, a - b)
}
return (heap.Pop(h)).(int)
}
``````