79 lines
1.6 KiB
Go
79 lines
1.6 KiB
Go
package aoc
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type Vector struct {
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Offset Point[int]
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Scale int
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}
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func (v Vector) Point() Point[int] {
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return v.Offset.Scale(v.Scale)
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}
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type Point[T integer] [2]T
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func (p Point[T]) Add(a Point[T]) Point[T] {
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return Point[T]{p[0] + a[0], p[1] + a[1]}
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}
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func (p Point[T]) Scale(m T) Point[T] {
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return Point[T]{p[0] * m, p[1] * m}
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}
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func (p Point[T]) Less(b Point[T]) bool {
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if p[0] != b[0] {
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return p[0] < b[0]
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}
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return p[1] < b[1]
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}
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func Transpose[T any](matrix [][]T) [][]T {
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rows, cols := len(matrix), len(matrix[0])
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m := make([][]T, cols)
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for i := range m {
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m[i] = make([]T, rows)
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}
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for i := 0; i < cols; i++ {
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for j := 0; j < rows; j++ {
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m[i][j] = matrix[j][i]
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}
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}
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return m
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}
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// NumPoints the number of the points inside an outline plus the number of points in the outline
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func NumPoints(outline []Point[int], borderLength int) int {
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// shoelace - find the float area in a shape
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sum := 0
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for _, p := range Pairwise(outline) {
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row1, col1 := p[0][0], p[0][1]
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row2, col2 := p[1][0], p[1][1]
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sum += row1*col2 - row2*col1
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}
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area := sum / 2
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// pick's theorem - find the number of points in a shape given its area
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return (ABS(area) - borderLength/2 + 1) + borderLength
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}
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type Map[I integer, T any] [][]T
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func (m *Map[I,T]) Get(p Point[I]) (Point[I], T, bool) {
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var zero T
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if !m.Valid(p) {
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return [2]I{0, 0}, zero, false
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}
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return p, (*m)[p[0]][p[1]], true
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}
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func (m *Map[I,T]) Size() (I, I) {
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if m == nil || len(*m) == 0 {
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return 0, 0
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}
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return I(len(*m)), I(len((*m)[0]))
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}
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func (m *Map[I,T]) Valid(p Point[I]) bool {
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rows, cols := m.Size()
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return p[0] >= 0 && p[0] < rows && p[1] >= 0 && p[1] < cols
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}
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