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day02.go
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day02.go
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// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package day02 solves AoC 2016 day 2.
package day02
import (
"strings"
"github.com/fis/aoc/glue"
)
func init() {
glue.RegisterSolver(2016, 2, glue.LineSolver(solve))
}
func solve(lines []string) ([]string, error) {
p1 := decode(lines)
p2 := decodeCross(lines)
return []string{p1, p2}, nil
}
func decode(sheet []string) string {
keypad := [3][3]byte{{'1', '2', '3'}, {'4', '5', '6'}, {'7', '8', '9'}}
x, y := 1, 1
var code strings.Builder
for _, steps := range sheet {
for _, step := range steps {
switch step {
case 'L':
x = max(x-1, 0)
case 'R':
x = min(x+1, 2)
case 'U':
y = max(y-1, 0)
case 'D':
y = min(y+1, 2)
}
}
code.WriteByte(keypad[y][x])
}
return code.String()
}
func decodeCross(sheet []string) string {
keypad := [5][5]byte{{0, 0, '1', 0, 0}, {0, '2', '3', '4', 0}, {'5', '6', '7', '8', '9'}, {0, 'A', 'B', 'C', 0}, {0, 0, 'D', 0, 0}}
x, y := 0, 2
var code strings.Builder
for _, steps := range sheet {
for _, step := range steps {
nx, ny := x, y
switch step {
case 'L':
nx = max(x-1, 0)
case 'R':
nx = min(x+1, 4)
case 'U':
ny = max(y-1, 0)
case 'D':
ny = min(y+1, 4)
}
if keypad[ny][nx] != 0 {
x, y = nx, ny
}
}
code.WriteByte(keypad[y][x])
}
return code.String()
}