go: add «1456. Maximum Number of Vowels in a Substring of Given Length»

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

go/maximum-number-of-vowels-in-a-substring-of-given-length.go

@@ -0,0 +1,33 @@
+package main
+
+func maxVowels(s string, k int) int {
+	isVowel := func(c byte) bool {
+		return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u'
+	}
+	countFirst := func() int {
+		count := 0
+		for i := 0; i < k; i++ {
+			if isVowel(s[i]) {
+				count++
+			}
+		}
+		return count
+	}
+
+	count := countFirst()
+
+	maxCount := count
+	for i := k; i < len(s); i++ {
+		if isVowel(s[i-k]) {
+			count--
+		}
+
+		if isVowel(s[i]) {
+			count++
+		}
+
+		maxCount = max(maxCount, count)
+	}
+
+	return maxCount
+}