go: add «2779. Maximum Beauty of an Array After Applying Operation»

URL:	https://leetcode.com/problems/maximum-beauty-of-an-array-after-applying-operation/
Signed-off-by: Matej Focko <me@mfocko.xyz>

go/maximum-beauty-of-an-array-after-applying-operation.go

@@ -0,0 +1,25 @@
+package main
+
+import "slices"
+
+func maximumBeauty(nums []int, k int) int {
+	if len(nums) == 1 {
+		return 1
+	}
+
+	maxValue := slices.Max(nums)
+
+	count := make([]int, maxValue+1)
+	for _, n := range nums {
+		count[max(0, n-k)]++
+		count[min(n+k+1, maxValue)]--
+	}
+
+	maxBeauty, runningSum := 0, 0
+	for _, x := range count {
+		runningSum += x
+		maxBeauty = max(maxBeauty, runningSum)
+	}
+
+	return maxBeauty
+}