accepted solution for "Max Robots on Budget" No 2398 hard

2398-max-num-robots-on-budget.go

@@ -1,11 +1,101 @@
 package main
 
+type Queue interface {
+	Enqueue(value int)
+	Dequeue() int
+	Peek() int
+	IsEmpty() bool
+}
+
+type MonoDecQueue struct {
+	elements []int
+}
+
+func NewMonoDecQueue() *MonoDecQueue {
+	return &MonoDecQueue{elements: make([]int, 0)}
+}
+
+func (q *MonoDecQueue) Enqueue(value int) {
+	for !q.IsEmpty() && q.elements[len(q.elements)-1] < value {
+		q.elements = q.elements[:len(q.elements)-1]
+	}
+	q.elements = append(q.elements, value)
+}
+
+func (q *MonoDecQueue) Dequeue() int {
+	if q.IsEmpty() {
+		panic("queue is empty")
+	}
+	value := q.elements[0]
+	q.elements = q.elements[1:]
+	return value
+}
+
+func (q *MonoDecQueue) Peek() int {
+	if q.IsEmpty() {
+		panic("queue is empty")
+	}
+	return q.elements[0]
+}
+
+func (q *MonoDecQueue) IsEmpty() bool {
+	return len(q.elements) == 0
+}
+
 func MaximumRobots(chargeTimes []int, runningCosts []int, budget int64) int {
 	l := len(chargeTimes)
 	if l != len(runningCosts) {
 		return 0
 	}
 
+	j := 0
+	prevJ := -1
+	s := 0
+	maxRobots := 0
+
+	q := NewMonoDecQueue()
+
+	for i := 0; i < l; i++ {
+
+		if j < i {
+			j = i
+		}
+
+		for ; j < l; j++ {
+			num := j - i + 1
+			if prevJ != j {
+				s += runningCosts[j]
+				q.Enqueue(chargeTimes[j])
+			}
+
+			prevJ = j
+			if int64(s*num+q.Peek()) <= budget {
+				if maxRobots <= num {
+					maxRobots = num
+				}
+			} else {
+				break
+			}
+		}
+
+		if !q.IsEmpty() {
+			if q.Peek() == chargeTimes[i] {
+				q.Dequeue()
+			}
+		}
+
+		s -= runningCosts[i]
+	}
+
+	return maxRobots
+}
+
+func MaximumRobotsEx(chargeTimes []int, runningCosts []int, budget int64) int {
+	l := len(chargeTimes)
+	if l != len(runningCosts) {
+		return 0
+	}
+
 	prevCharges := make([]int, l)
 	prevCosts := make([]int, l)
 	maxWndRobots := make([]int, l+1)
@@ -17,8 +107,8 @@ func MaximumRobots(chargeTimes []int, runningCosts []int, budget int64) int {
 
 		begin := 0
 		end := wnd - 1
-
-		for w := 0; w < windows; w++ {
+		w := 0
+		for w = 0; w < windows; w++ {
 			m := chargeTimes[end]
 
 			if m > prevCharges[w] {