add new solutions

solutions/0/q54/solution.go

@@ -0,0 +1,40 @@
+package q54
+
+import "math"
+
+var dirs = [4][2]int{
+	{1, 0},  // right
+	{0, 1},  // down
+	{-1, 0}, // left
+	{0, -1}, // up
+}
+
+const VISITED = math.MinInt
+
+func spiralOrder(matrix [][]int) []int {
+	w, h := len(matrix[0]), len(matrix)
+	cnt := w * h
+	ret := make([]int, cnt)
+
+	x, y := 0, 0
+	dir := 0
+	vect := dirs[dir]
+
+	for i := range cnt {
+		ret[i] = matrix[y][x]
+		matrix[y][x] = VISITED
+
+		// Can move?
+		nextX, nextY := x+vect[0], y+vect[1]
+		if nextX < 0 || nextY < 0 || nextX == w || nextY == h || matrix[nextY][nextX] == VISITED {
+			dir = (dir + 1) % 4
+			vect = dirs[dir]
+			nextX, nextY = x+vect[0], y+vect[1]
+		}
+		x, y = nextX, nextY
+	}
+
+	return ret
+}
+
+var _ = spiralOrder