package main
//file to implement expanding/shrinking intlist with a map
import "fmt"

type IntList struct {
	list map[int]int
	//for keeping track of placement indices and insertion spots
	record map[string]int
}

//creates an IntList and returns it
func createIntList() IntList {
	lst := IntList{list:make(map[int]int), record:make(map[string]int)}
	lst.record["insert"] = 0
	lst.record["last"] = -1
	return lst
}
//appends a new element to the end of the list, and updates the insertion and last element positions
func (il IntList) push(elem int) {
	il.list[il.record["insert"]] = elem
	il.record["insert"] += 1
	il.record["last"] += 1
}

func (il IntList) pop() int {
	popped, has := il.list[il.record["last"]]
	if has {
		delete(il.list, il.record["last"])
		il.record["last"] -= 1
		il.record["insert"] -= 1
		return popped
	}
	return -1
}


func main() {
  tester := createIntList()
  tester.push(5)
  tester.push(8)
  fmt.Println(tester)
  fmt.Println(tester.pop())
  fmt.Println(tester)
}
/*{map[0:5 1:8] map[insert:2 last:1]}
8
{map[0:5] map[last:0 insert:1]}
   */