Spiral Matrix IV

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */

func next(head *ListNode) (*ListNode, int) {
    if head != nil {
        val := head.Val
        return head.Next, val
    }
    return nil, -1
}

func fillBorder(m1, m2, n1, n2 int, head *ListNode, matrix [][]int) {
    // North
    if n2-n1 < 1 || m2-m1 < 1 {
        return
    }
    for i := n1; i < n2; i++ {
        head, matrix[m1][i] = next(head)
    }

    // East
    if m2-m1 < 1 {
        return
    }
    for j := m1 + 1; j < m2; j++ {
        head, matrix[j][n2-1] = next(head)
    }

    // South
    if n2-n1 <= 1 || m2-m1 <= 1 {
        return
    }
    for i := n2 - 2; i >= n1; i-- {
        head, matrix[m2-1][i] = next(head)
    }

    // West
    if m2-m1 <= 1 {
        return
    }
    for j := m2 - 2; j > m1; j-- {
        head, matrix[j][m1] = next(head)
    }
    fillBorder(m1+1, m2-1, n1+1, n2-1, head, matrix)
}

func spiralMatrix(m int, n int, head *ListNode) [][]int {
    matrix := make([][]int, m)
    for i, _ := range matrix {
        matrix[i] = make([]int, n)
    }

    fillBorder(0, m, 0, n, head, matrix)

    return matrix
}