package main

import (
	"slices"
	"testing"
)

func TestExamples(t *testing.T) {
	cases := []struct {
		start    []uint64
		steps    int
		expected []uint64
	}{
		{[]uint64{0, 1, 10, 99, 999}, 1,
			[]uint64{1, 2024, 1, 0, 9, 9, 2021976},
		},
		{[]uint64{125, 17}, 6,
			[]uint64{2097446912, 14168, 4048, 2, 0, 2, 4, 40, 48, 2024, 40, 48, 80, 96, 2, 8, 6, 7, 6, 0, 3, 2},
		},
	}
	for _, c := range cases {
		actual := make([]uint64, 0, 64)
		previous := make([]uint64, len(c.start), 64)
		copy(previous, c.start)

		for i := 0; i < c.steps; i++ {
			actual = actual[:0]
			actual = step(previous, actual)
			if len(actual) > len(previous) {
				previous = make([]uint64, len(actual), 2*len(previous))
			}
			copy(previous, actual)
		}

		if !slices.Equal(actual, c.expected) {
			t.Errorf("expected %v; got %v", c.expected, actual)
		}
	}
}

func TestExample2(t *testing.T) {
	start := []uint64{125, 17}
	expected := 55312

	actual := make([]uint64, 0, 64)
	previous := make([]uint64, len(start), 64)
	copy(previous, start)

	for i := 0; i < 25; i++ {
		actual = actual[:0]
		actual = step(previous, actual)
		if len(actual) > len(previous) {
			previous = make([]uint64, len(actual), 2*len(previous))
		}
		copy(previous, actual)
	}
	if len(actual) != expected {
		t.Errorf("expected %d; got %d", expected, len(actual))
	}
}