go: add «1267. Count Servers that Communicate»

URL:	https://leetcode.com/problems/count-servers-that-communicate/
Signed-off-by: Matej Focko <me@mfocko.xyz>

go/count-servers-that-communicate.go

@@ -0,0 +1,40 @@
+package main
+
+const (
+	NOT_SEEN int = -1
+	SERVER   int = 1
+)
+
+func countServers(grid [][]int) int {
+	count := 0
+
+	inCol := make([]int, len(grid[0]))
+	lastInRow := make([]int, len(grid))
+	for y, _ := range lastInRow {
+		lastInRow[y] = NOT_SEEN
+	}
+
+	for y, row := range grid {
+		countInRow := 0
+		for x, state := range row {
+			if state == SERVER {
+				countInRow++
+				inCol[x]++
+				lastInRow[y] = x
+			}
+		}
+
+		if countInRow > 1 {
+			count += countInRow
+			lastInRow[y] = NOT_SEEN
+		}
+	}
+
+	for y, _ := range grid {
+		if lastInRow[y] != NOT_SEEN && inCol[lastInRow[y]] > 1 {
+			count++
+		}
+	}
+
+	return count
+}