leetcode-go/medium/54.go

package main

func spiralOrder(matrix [][]int) (res []int) {
	if len(matrix) == 0 {
		return
	}
	w, h := len(matrix[0]), len(matrix)
	for x, y := 0, 0; w > 0 && h > 0; w, h, x, y = w-2, h-2, x+1, y+1 {
		if h == 1 {
			// 1 2 3 4
			res = append(res, matrix[y][x:x+w]...)
			return
		} else if w == 1 {
			// 1
			// 2
			// 3
			// 4
			for i := 0; i < h; i, y = i+1, y+1 {
				res = append(res, matrix[y][x])
			}
			return
		}
		// 1   2   3   4  loop1 -> 1  2  3
		// 12   ...    5  loop2 -> 4  5  6
		// 11   ...    6  loop3 -> 7  8  9
		// 10  9   8   7  loop4 -> 10 11 12
		var xSpeed, ySpeed, length int
		for loop := 0; loop < 4; loop++ {
			switch loop {
			case 0:
				xSpeed, ySpeed, length = 1, 0, w-1
			case 1:
				xSpeed, ySpeed, length = 0, 1, h-1
			case 2:
				xSpeed, ySpeed, length = -1, 0, w-1
			default:
				xSpeed, ySpeed, length = 0, -1, h-1
			}
			for i := 0; i < length; i++ {
				res = append(res, matrix[y][x])
				x += xSpeed
				y += ySpeed
			}
		}
	}
	return
}

/* func main() {
	m1 := [][]int{
		{11, 22, 33, 44, 55},
		{16, 27, 38, 49, 50},
		{11, 23, 35, 47, 59},
		{12, 24, 36, 48, 50},
		{15, 24, 33, 42, 51},
	}
	fmt.Println(spiralOrder(m1))
	m2 := [][]int{
		{11, 22, 11},
		{16, 27, 33},
		{11, 23, 24},
		{12, 13, 44},
	}
	fmt.Println(spiralOrder(m2))
	m3 := [][]int{
		{11},
		{16},
		{11},
	}
	fmt.Println(spiralOrder(m3))
} */