"Shortest Subarray with Sum at Least K" hard task No 862 sliding window with prefix sums

862-shortest-subarray-with-sum-at-least-k.go

@@ -5,57 +5,28 @@ func ShortestSubarray(nums []int, k int) int {
 		return -1
 	}
 
-	queue := [100000]int{}
-	queue2 := [100000]int{}
+	sz := 999999
+	prefix := make([]int, len(nums)+1)
 
-	qIterator := &queue
-	q2Iterator := &queue2
-
-	t := qIterator
-
-	qEndPtr := -1
-	qBeginPtr := -1
-
-	q2EndPtr := -1
-	q2BeginPtr := -1
-
-	lenNums := len(nums)
-	nums2 := [100000]int{}
-
-	for i, n := range nums {
-		qEndPtr++
-		qIterator[qEndPtr] = n
-
-		nums2[i] = n
-
-		if n >= k {
-			return 1
-		}
+	for i := 1; i <= len(nums); i++ {
+		prefix[i] = prefix[i-1] + nums[i-1]
 	}
 
-	wndSz := 0
-	i := 0
-
-	for wndSz = 2; wndSz <= lenNums; wndSz++ {
-		for i = wndSz - 1; i < lenNums; i++ {
-			qBeginPtr++
-			q2EndPtr++
-			q2Iterator[q2EndPtr] = qIterator[qBeginPtr] + nums2[i]
-			if q2Iterator[q2EndPtr] >= k {
-				return wndSz
+	for i := 0; i < len(nums); i++ {
+		for j := i; j < len(nums); j++ {
+			sum := prefix[j+1] - prefix[i]
+			if sum >= k {
+				l := j - i + 1
+				if sz > l {
+					sz = l
+				}
 			}
 		}
-
-		t = qIterator
-		qIterator = q2Iterator
-		q2Iterator = t
-
-		qBeginPtr = q2BeginPtr
-		qEndPtr = q2EndPtr
-
-		q2BeginPtr = -1
-		q2EndPtr = -1
 	}
 
-	return -1
+	if sz == 999999 {
+		sz = -1
+	}
+
+	return sz
 }