go: add «1052. Grumpy Bookstore Owner»

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

go/grumpy-bookstore-owner.go

@@ -0,0 +1,29 @@
+package main
+
+func maxSatisfied(customers []int, grumpy []int, minutes int) int {
+	// count always satisfied customers
+	satisfied := 0
+	for i, count := range customers {
+		satisfied += count * (1 - grumpy[i])
+	}
+
+	// get the initial run
+	unsatisfied := 0
+	for i := 0; i < minutes; i++ {
+		unsatisfied += customers[i] * grumpy[i]
+	}
+
+	maxCoverage := unsatisfied
+	for i := minutes; i < len(customers); i++ {
+		// remove from the start
+		unsatisfied -= customers[i-minutes] * grumpy[i-minutes]
+
+		// add from the end
+		unsatisfied += customers[i] * grumpy[i]
+
+		// update max coverage
+		maxCoverage = max(maxCoverage, unsatisfied)
+	}
+
+	return maxCoverage + satisfied
+}