add new solutions

solutions/2/q200/solution.go

@@ -0,0 +1,31 @@
+package q200
+
+const (
+	VISITED byte = '.'
+	LAND    byte = '1'
+)
+
+func traverse(grid [][]byte, x, y int) int {
+	if x < 0 || y < 0 || x >= len(grid[0]) || y >= len(grid) || grid[y][x] != LAND {
+		return 0
+	}
+
+	grid[y][x] = VISITED
+	traverse(grid, x+1, y)
+	traverse(grid, x-1, y)
+	traverse(grid, x, y+1)
+	traverse(grid, x, y-1)
+	return 1
+}
+
+func numIslands(grid [][]byte) int {
+	count := 0
+	for y := range grid {
+		for x := range grid[y] {
+			count += traverse(grid, x, y)
+		}
+	}
+	return count
+}
+
+var _ = numIslands