go: add «1051. Height Checker»

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

go/height-checker.go

@@ -0,0 +1,25 @@
+package height_checker
+
+func heightChecker(heights []int) int {
+	// count the heights
+	var counts [100]int
+	for _, h := range heights {
+		counts[h-1]++
+	}
+
+	incorrect := 0
+
+	expectedH := 1
+	for _, h := range heights {
+		for expectedH <= 100 && counts[expectedH-1] == 0 {
+			expectedH++
+		}
+		counts[expectedH-1]--
+
+		if expectedH != h {
+			incorrect++
+		}
+	}
+
+	return incorrect
+}