add new solutions

solutions/9/q994/solution.go

@@ -0,0 +1,48 @@
+package q994
+
+func orangesRotting(grid [][]int) int {
+	w, h := len(grid[0]), len(grid)
+	queue := make([][3]int, 0, w+h) // row, col, minute
+	nFresh, nRot := 0, 0
+
+	for r := range grid {
+		for c := range grid[0] {
+			switch grid[r][c] {
+			case 1:
+				nFresh++
+			case 2:
+				nRot++
+				queue = append(queue, [3]int{r, c, 0})
+			}
+		}
+	}
+
+	var rot = func(r, c, minute int) {
+		if r < 0 || c < 0 || r >= h || c >= w || grid[r][c] != 1 {
+			return
+		}
+		grid[r][c] = 2
+		nFresh--
+		nRot++
+		queue = append(queue, [3]int{r, c, minute})
+	}
+
+	minutes := 0
+	for ; len(queue) > 0; queue = queue[1:] {
+		cur := queue[0]
+		r, c, minute := cur[0], cur[1], cur[2]
+		minutes = max(minute, minutes)
+
+		rot(r, c+1, minute+1)
+		rot(r, c-1, minute+1)
+		rot(r+1, c, minute+1)
+		rot(r-1, c, minute+1)
+	}
+
+	if nFresh == 0 {
+		return minutes
+	}
+	return -1
+}
+
+var _ = orangesRotting