How to Sort a 2D Array in Go?

Sorting a Two-Dimensional Array in Go

In Go, sorting a two-dimensional array requires defining a custom sorting criterion. One approach is to implement the sort.Interface to provide the necessary methods for sorting:

type Matrix [3][3]int

func (m Matrix) Len() int { return len(m) }
func (m Matrix) Less(i, j int) bool {
    for x := range m[i] {
        if m[i][x] == m[j][x] {
            continue
        }
        return m[i][x] < m[j][x]
    }
    return false
}

func (m *Matrix) Swap(i, j int) { m[i], m[j] = m[j], m[i] }

Here, Matrix implements sort.Interface by defining the Len(), Less(), and Swap() methods. Len() returns the length of the matrix, Less() compares two rows of the matrix element-wise, and Swap() swaps two rows.

func main() {
    m := Matrix(matrix)
    sort.Sort(&m)
}

In this example, matrix is a predefined two-dimensional array, and m is a copy of matrix that implements sort.Interface. By passing &m to sort.Sort(), the matrix is sorted in-place.

Another approach is to use the sort.Slice() function:

sort.Slice(matrix[:], func(i, j int) bool {
    for x := range matrix[i] {
        if matrix[i][x] == matrix[j][x] {
            continue
        }
        return matrix[i][x] < matrix[j][x]
    }
    return false
})

fmt.Println(matrix)

Here, matrix[:] converts the matrix to a slice, and the provided anonymous function defines the sorting criterion. By passing the slice and the function to sort.Slice(), the matrix is sorted in-place.

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