add new solutions

solutions/7/q744/solution.go

@@ -0,0 +1,21 @@
+package q744
+
+func nextGreatestLetter(letters []byte, target byte) byte {
+	l, r := 0, len(letters)
+	for l < r {
+		m := (l + r) / 2
+
+		if letters[m] <= target {
+			l = m + 1
+		} else {
+			r = m
+		}
+	}
+
+	if l == len(letters) {
+		l = 0
+	}
+	return letters[l]
+}
+
+var _ = nextGreatestLetter