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day06.go
60 lines (54 loc) · 1.42 KB
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day06.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 day06 solves AoC 2016 day 6.
package day06
import (
"math"
"github.com/fis/aoc/glue"
)
func init() {
glue.RegisterSolver(2016, 6, glue.LineSolver(solve))
}
func solve(lines []string) ([]string, error) {
p1, p2 := decode(lines)
return []string{p1, p2}, nil
}
func decode(lines []string) (string, string) {
N := len(lines[0])
m1, m2 := make([]byte, N), make([]byte, N)
for i := 0; i < N; i++ {
var freqs [26]int
for _, line := range lines {
if b := line[i]; b >= 'a' && b <= 'z' {
freqs[b-'a']++
}
}
maxB, maxF, minB, minF := byte(0), math.MinInt, byte(0), math.MaxInt
for b := byte(0); b < 26; b++ {
f := freqs[b]
if f == 0 {
continue
}
if f > maxF {
maxB, maxF = b, f
}
if f < minF {
minB, minF = b, f
}
}
m1[i] = 'a' + maxB
m2[i] = 'a' + minB
}
return string(m1), string(m2)
}