go: add «1508. Range Sum of Sorted Subarray Sums»

Signed-off-by: Matej Focko <me@mfocko.xyz>

go/range-sum-of-sorted-subarray-sums.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"cmp"
+
+	pq "github.com/emirpasic/gods/v2/queues/priorityqueue"
+)
+
+const MOD int = 1_000_000_007
+
+type Sum struct {
+	index int
+	sum   int
+}
+
+func cmpSum(a, b Sum) int {
+	return cmp.Compare(a.sum, b.sum)
+}
+
+func rangeSum(nums []int, n int, left int, right int) int {
+	q := pq.NewWith[Sum](cmpSum)
+
+	for i, num := range nums {
+		q.Enqueue(Sum{index: i, sum: num})
+	}
+
+	total := 0
+	for i := 1; i <= right; i++ {
+		s, _ := q.Dequeue()
+
+		if i >= left {
+			total = (total + s.sum) % MOD
+		}
+
+		if s.index < n-1 {
+			s.index++
+			s.sum += nums[s.index]
+			q.Enqueue(s)
+		}
+	}
+
+	return total
+}