Partial solution for 10.1. We've got grouping, but still need sorting and some printing cleanup.

2018/internal/day10/grid.go

@@ -0,0 +1,46 @@
+// Unused solution: this works fine for the example, but doesn't work at all for the
+// real input data.
+package day10
+
+import "fmt" // debug
+
+// AnalyzePoints tries to determine whether the data looks sufficiently ordered.
+// It returns 'true' if it thinks we've got letters.
+func AnalyzePoints(points []*Point) bool {
+	pointArr := makeBuffer(points)
+
+	// count adjacencies
+	count := 0
+
+	for y := 0; y < len(pointArr[0]); y++ {
+		for x := 0; x < len(pointArr); x++ {
+			if pointArr[x][y] != '#' {
+				continue
+			}
+
+			if checkPoint(pointArr, x-1, y) ||
+				checkPoint(pointArr, x+1, y) ||
+				checkPoint(pointArr, x, y-1) ||
+				checkPoint(pointArr, x, y+1) {
+				count++
+			}
+		}
+	}
+
+	fmt.Println(float64(count) / float64(len(points))) // debug
+	return float64(count) >= 0.8*float64(len(points))
+}
+
+// Checks the point in the grid. If it is '#' returns true.
+func checkPoint(grid [][]byte, x, y int) bool {
+	if x < 0 || x >= len(grid) ||
+		y < 0 || y >= len(grid[0]) {
+		return false
+	}
+
+	if grid[x][y] == '#' {
+		return true
+	}
+
+	return false
+}