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day5.go
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// You can edit this code!
// Click here and start typing.
package main
import (
"fmt"
"strconv"
"strings"
)
func main() {
fmt.Println(part1(input1))
fmt.Println(part1(input2))
fmt.Println(part2(input1))
fmt.Println(part2(input2))
}
func part1(input string) string {
stacks, instructions := parse(input)
for _, ins := range instructions {
for n := 0; n < ins.N; n++ {
var head string
j := len(stacks[ins.From]) - 1
stacks[ins.From], head = stacks[ins.From][:j], stacks[ins.From][j]
stacks[ins.To] = append(stacks[ins.To], head)
}
}
var out string
for _, s := range stacks {
out += s[len(s)-1]
}
return out
}
func part2(input string) string {
stacks, instructions := parse(input)
for _, ins := range instructions {
var rest []string
i := len(stacks[ins.From]) - ins.N
stacks[ins.From], rest = stacks[ins.From][:i], stacks[ins.From][i:]
stacks[ins.To] = append(stacks[ins.To], rest...)
}
var out string
for _, s := range stacks {
out += s[len(s)-1]
}
return out
}
type Instruction struct {
N int
From int
To int
}
func parse(input string) ([][]string, []Instruction) {
var isIns bool
var rawStacks []string
var instructions []Instruction
rows := strings.Split(input, "\n")
for _, row := range rows {
if row == "" {
isIns = true
continue
}
if isIns {
// Parse the instruction `move 1 from 2 to 1`
// 1. Split by whitespaces: [move, 1, from, 2, to, 1]
// 2. Take the values at odd number indices
// 3. Convert to int
matches := strings.Fields(row)
instructions = append(instructions, Instruction{
N: toInt(matches[1]),
From: toInt(matches[3]) - 1,
To: toInt(matches[5]) - 1,
})
} else {
rawStacks = append(rawStacks, row)
}
}
nStacks := (len(rawStacks[0]) + 1) / 4
stacks := make([][]string, nStacks)
rawStacks = rawStacks[:len(rawStacks)-1]
for i := len(rawStacks) - 1; i > -1; i-- {
stack := rawStacks[i]
for s := 0; s < nStacks; s++ {
pos := 1 + s*4
v := string(stack[pos])
if v != " " {
stacks[s] = append(stacks[s], v)
}
}
}
return stacks, instructions
}
func toInt(s string) int {
n, err := strconv.Atoi(s)
if err != nil {
panic(err)
}
return n
}
var input1 = ` [D]
[N] [C]
[Z] [M] [P]
1 2 3
move 1 from 2 to 1
move 3 from 1 to 3
move 2 from 2 to 1
move 1 from 1 to 2`
var input2 = ` [G] [R] [P]
[H] [W] [T] [P] [H]
[F] [T] [P] [B] [D] [N]
[L] [T] [M] [Q] [L] [C] [Z]
[C] [C] [N] [V] [S] [H] [V] [G]
[G] [L] [F] [D] [M] [V] [T] [J] [H]
[M] [D] [J] [F] [F] [N] [C] [S] [F]
[Q] [R] [V] [J] [N] [R] [H] [G] [Z]
1 2 3 4 5 6 7 8 9
move 5 from 8 to 2
move 2 from 4 to 5
move 3 from 3 to 9
move 4 from 1 to 8
move 5 from 9 to 1
move 3 from 3 to 8
move 2 from 4 to 7
move 6 from 6 to 5
move 5 from 2 to 4
move 2 from 9 to 1
move 1 from 7 to 1
move 4 from 7 to 3
move 5 from 1 to 5
move 3 from 1 to 4
move 8 from 5 to 3
move 7 from 3 to 2
move 10 from 4 to 7
move 1 from 7 to 3
move 1 from 6 to 2
move 3 from 8 to 4
move 4 from 3 to 2
move 1 from 1 to 2
move 4 from 3 to 1
move 2 from 1 to 7
move 3 from 5 to 1
move 7 from 8 to 4
move 9 from 5 to 1
move 9 from 2 to 7
move 6 from 4 to 9
move 14 from 7 to 5
move 2 from 1 to 4
move 6 from 7 to 1
move 4 from 4 to 9
move 6 from 2 to 8
move 2 from 4 to 9
move 2 from 9 to 3
move 3 from 8 to 3
move 5 from 9 to 4
move 1 from 2 to 9
move 5 from 5 to 3
move 3 from 2 to 7
move 1 from 1 to 4
move 3 from 7 to 5
move 4 from 9 to 6
move 2 from 9 to 3
move 5 from 1 to 6
move 7 from 6 to 5
move 1 from 2 to 3
move 10 from 1 to 5
move 1 from 8 to 3
move 14 from 3 to 7
move 1 from 8 to 4
move 2 from 6 to 1
move 28 from 5 to 9
move 1 from 2 to 1
move 5 from 4 to 6
move 2 from 4 to 3
move 13 from 7 to 8
move 1 from 3 to 5
move 1 from 5 to 2
move 1 from 3 to 6
move 1 from 5 to 6
move 22 from 9 to 1
move 1 from 2 to 7
move 3 from 9 to 5
move 2 from 7 to 5
move 18 from 1 to 4
move 7 from 8 to 3
move 4 from 6 to 8
move 2 from 5 to 8
move 5 from 3 to 9
move 2 from 5 to 1
move 3 from 6 to 8
move 1 from 5 to 9
move 2 from 3 to 6
move 10 from 1 to 5
move 15 from 8 to 6
move 10 from 6 to 8
move 1 from 9 to 4
move 1 from 1 to 3
move 4 from 4 to 3
move 5 from 3 to 5
move 9 from 5 to 6
move 13 from 6 to 5
move 8 from 5 to 7
move 8 from 9 to 6
move 2 from 6 to 4
move 2 from 6 to 2
move 3 from 7 to 4
move 2 from 2 to 8
move 1 from 5 to 4
move 3 from 7 to 9
move 1 from 5 to 9
move 5 from 6 to 9
move 10 from 8 to 3
move 3 from 8 to 1
move 5 from 9 to 2
move 1 from 6 to 4
move 4 from 5 to 6
move 7 from 3 to 7
move 5 from 6 to 5
move 19 from 4 to 8
move 15 from 8 to 3
move 2 from 1 to 5
move 7 from 5 to 9
move 2 from 7 to 2
move 3 from 3 to 8
move 5 from 5 to 8
move 10 from 9 to 3
move 1 from 4 to 2
move 10 from 8 to 3
move 29 from 3 to 2
move 2 from 3 to 4
move 1 from 1 to 5
move 2 from 8 to 4
move 1 from 9 to 1
move 1 from 3 to 9
move 1 from 1 to 9
move 2 from 3 to 4
move 33 from 2 to 1
move 2 from 2 to 4
move 1 from 3 to 1
move 22 from 1 to 2
move 6 from 4 to 9
move 4 from 7 to 1
move 16 from 1 to 4
move 3 from 7 to 6
move 2 from 9 to 4
move 1 from 5 to 2
move 9 from 4 to 2
move 1 from 6 to 5
move 7 from 4 to 2
move 6 from 9 to 8
move 4 from 4 to 9
move 4 from 8 to 3
move 2 from 4 to 3
move 2 from 2 to 5
move 2 from 5 to 2
move 1 from 5 to 6
move 3 from 9 to 5
move 1 from 6 to 8
move 2 from 6 to 5
move 1 from 3 to 2
move 1 from 8 to 4
move 2 from 8 to 2
move 5 from 5 to 6
move 44 from 2 to 8
move 1 from 4 to 8
move 3 from 6 to 8
move 2 from 6 to 2
move 37 from 8 to 3
move 1 from 9 to 4
move 1 from 2 to 5
move 5 from 8 to 6
move 1 from 4 to 6
move 1 from 2 to 4
move 16 from 3 to 2
move 1 from 4 to 5
move 1 from 8 to 3
move 4 from 8 to 2
move 1 from 8 to 7
move 2 from 5 to 8
move 15 from 2 to 4
move 5 from 6 to 3
move 1 from 7 to 4
move 1 from 8 to 9
move 1 from 6 to 7
move 1 from 8 to 3
move 2 from 2 to 8
move 1 from 9 to 3
move 2 from 8 to 4
move 1 from 4 to 6
move 33 from 3 to 7
move 1 from 6 to 3
move 1 from 4 to 8
move 1 from 8 to 9
move 4 from 4 to 3
move 9 from 4 to 7
move 3 from 4 to 8
move 11 from 7 to 2
move 14 from 7 to 6
move 1 from 8 to 3
move 1 from 9 to 5
move 1 from 5 to 1
move 8 from 2 to 9
move 1 from 8 to 7
move 6 from 3 to 6
move 18 from 6 to 4
move 1 from 2 to 7
move 1 from 3 to 6
move 14 from 4 to 2
move 4 from 4 to 3
move 3 from 6 to 3
move 19 from 2 to 6
move 16 from 6 to 8
move 1 from 1 to 8
move 16 from 8 to 7
move 3 from 9 to 4
move 3 from 6 to 2
move 3 from 4 to 7
move 4 from 3 to 2
move 2 from 2 to 4
move 4 from 9 to 8
move 5 from 2 to 8
move 29 from 7 to 5
move 6 from 8 to 2
move 2 from 3 to 4
move 2 from 2 to 6
move 1 from 3 to 5
move 4 from 2 to 6
move 8 from 7 to 5
move 1 from 7 to 5
move 2 from 8 to 6
move 1 from 8 to 7
move 6 from 6 to 1
move 2 from 7 to 6
move 1 from 9 to 7
move 3 from 1 to 7
move 3 from 6 to 1
move 1 from 7 to 6
move 3 from 1 to 6
move 1 from 1 to 5
move 4 from 6 to 3
move 2 from 4 to 2
move 38 from 5 to 6
move 3 from 3 to 8
move 4 from 8 to 6
move 22 from 6 to 8
move 1 from 7 to 8
move 2 from 6 to 2
move 2 from 5 to 2
move 2 from 2 to 1
move 2 from 4 to 6
move 2 from 2 to 1
move 1 from 1 to 9
move 2 from 8 to 5
move 2 from 2 to 8
move 2 from 5 to 2
move 2 from 7 to 2
move 1 from 3 to 1
move 4 from 1 to 8
move 1 from 9 to 5
move 1 from 1 to 7
move 1 from 2 to 8
move 29 from 8 to 3
move 15 from 3 to 2
move 12 from 2 to 5
move 1 from 1 to 6
move 3 from 2 to 1
move 6 from 3 to 8
move 2 from 3 to 9
move 1 from 6 to 7
move 12 from 5 to 8
move 2 from 7 to 1
move 2 from 1 to 4
move 2 from 4 to 2
move 1 from 5 to 8
move 1 from 3 to 6
move 2 from 3 to 4
move 3 from 1 to 4
move 5 from 8 to 9
move 4 from 4 to 2
move 5 from 9 to 6
move 26 from 6 to 8
move 7 from 2 to 8
move 3 from 3 to 1
move 1 from 6 to 4
move 14 from 8 to 6
move 2 from 1 to 2
move 1 from 1 to 3
move 18 from 8 to 5
move 15 from 8 to 2
move 5 from 6 to 8
move 4 from 5 to 8
move 7 from 2 to 5
move 2 from 9 to 6
move 1 from 2 to 1
move 7 from 2 to 3
move 7 from 8 to 1
move 2 from 6 to 3
move 1 from 4 to 6
move 2 from 8 to 6
move 10 from 3 to 9
move 18 from 5 to 8
move 1 from 4 to 6
move 2 from 1 to 9
move 12 from 6 to 9
move 1 from 6 to 9
move 9 from 8 to 4
move 6 from 1 to 2
move 3 from 8 to 9
move 14 from 9 to 8
move 5 from 4 to 9
move 2 from 4 to 5
move 16 from 8 to 5
move 12 from 5 to 4
move 7 from 5 to 1
move 1 from 1 to 8
move 1 from 5 to 8
move 1 from 4 to 9
move 8 from 2 to 7
move 12 from 4 to 3
move 2 from 2 to 5
move 1 from 3 to 2
move 3 from 5 to 4
move 1 from 4 to 8
move 3 from 4 to 9
move 18 from 9 to 8
move 8 from 3 to 1
move 5 from 8 to 1
move 1 from 2 to 5
move 3 from 7 to 1
move 3 from 7 to 5
move 1 from 8 to 9
move 5 from 9 to 7
move 2 from 3 to 6
move 16 from 1 to 4
move 14 from 8 to 6
move 2 from 5 to 6
move 4 from 1 to 6
move 3 from 4 to 9
move 15 from 6 to 1
move 5 from 4 to 3
move 2 from 8 to 2
move 6 from 4 to 3
move 15 from 1 to 5
move 14 from 5 to 3
move 5 from 6 to 2
move 2 from 4 to 7
move 1 from 1 to 6
move 2 from 3 to 4
move 3 from 8 to 1
move 1 from 5 to 1
move 5 from 7 to 1
move 7 from 1 to 3
move 3 from 6 to 2
move 4 from 9 to 5
move 2 from 4 to 3
move 4 from 7 to 9
move 8 from 2 to 9
move 1 from 9 to 1
move 2 from 2 to 8
move 11 from 9 to 1
move 6 from 5 to 1
move 21 from 3 to 2
move 1 from 8 to 5
move 5 from 1 to 7
move 12 from 1 to 8
move 1 from 5 to 2
move 5 from 3 to 2
move 4 from 7 to 2
move 1 from 7 to 8
move 13 from 2 to 5
move 13 from 2 to 5
move 2 from 2 to 1
move 1 from 1 to 9
move 26 from 5 to 4
move 3 from 2 to 7
move 2 from 3 to 9
move 1 from 1 to 6
move 5 from 3 to 2
move 2 from 9 to 6
move 1 from 1 to 8
move 3 from 1 to 6
move 24 from 4 to 9
move 13 from 9 to 1
move 2 from 6 to 2
move 3 from 7 to 5
move 2 from 9 to 7
move 8 from 8 to 3
move 4 from 8 to 5
move 2 from 7 to 2
move 8 from 9 to 4
move 10 from 1 to 2
move 1 from 9 to 1
move 1 from 9 to 2
move 4 from 3 to 2
move 4 from 1 to 8
move 3 from 4 to 8
move 12 from 2 to 3
move 3 from 4 to 6
move 5 from 3 to 2
move 9 from 3 to 9
move 4 from 2 to 9
move 1 from 3 to 7
move 6 from 8 to 2
move 4 from 6 to 8
move 1 from 3 to 8
move 6 from 9 to 1
move 2 from 1 to 8
move 5 from 5 to 8
move 3 from 6 to 8
move 1 from 5 to 1
move 7 from 8 to 2
move 1 from 1 to 4
move 1 from 4 to 6
move 1 from 9 to 4
move 1 from 5 to 9
move 1 from 4 to 7
move 12 from 8 to 2
move 4 from 4 to 3
move 2 from 3 to 1
move 1 from 7 to 2
move 1 from 6 to 8
move 1 from 8 to 6
move 4 from 9 to 3
move 1 from 9 to 3
move 13 from 2 to 3
move 3 from 1 to 7
move 2 from 9 to 4
move 2 from 1 to 9
move 2 from 7 to 2
move 1 from 4 to 1
move 2 from 7 to 5
move 14 from 3 to 8
move 1 from 8 to 5
move 2 from 1 to 4
move 2 from 3 to 4
move 2 from 3 to 4
move 10 from 8 to 3
move 2 from 4 to 8
move 1 from 9 to 3
move 3 from 2 to 3
move 16 from 2 to 4
move 1 from 8 to 5
move 11 from 3 to 4
move 2 from 3 to 7
move 3 from 5 to 1
move 1 from 1 to 2
move 3 from 2 to 5
move 1 from 1 to 9
move 2 from 7 to 4
move 8 from 4 to 3
move 1 from 6 to 7
move 1 from 8 to 6
move 1 from 5 to 1
move 6 from 3 to 5
move 2 from 1 to 3
move 5 from 5 to 7
move 2 from 7 to 2
move 2 from 3 to 4
move 4 from 7 to 1
move 1 from 6 to 8
move 1 from 2 to 1
move 3 from 1 to 6
move 2 from 9 to 6
move 8 from 2 to 1
move 2 from 6 to 2
move 2 from 6 to 3
move 6 from 3 to 5
move 2 from 4 to 6
move 2 from 2 to 9
move 1 from 8 to 6
move 2 from 6 to 5
move 1 from 9 to 1
move 11 from 5 to 8
move 7 from 8 to 6
move 23 from 4 to 1
move 1 from 5 to 9
move 1 from 4 to 6
move 2 from 4 to 8
move 1 from 3 to 1
move 6 from 8 to 3
move 2 from 9 to 6
move 3 from 6 to 1
move 3 from 8 to 7
move 1 from 3 to 6
move 18 from 1 to 2
move 5 from 3 to 8
move 13 from 2 to 9
move 5 from 9 to 7
move 1 from 8 to 6
move 5 from 2 to 6
move 2 from 1 to 7
move 9 from 7 to 8
move 11 from 8 to 6
move 2 from 9 to 4
move 16 from 6 to 1
move 2 from 4 to 6
move 1 from 8 to 9
move 1 from 7 to 6
move 8 from 1 to 5
move 3 from 6 to 5
move 8 from 6 to 4
move 7 from 9 to 5
move 1 from 8 to 1
move 6 from 5 to 1
move 9 from 5 to 7
move 4 from 7 to 9
move 1 from 4 to 8
move 1 from 8 to 3
move 1 from 1 to 8
move 1 from 8 to 7
move 22 from 1 to 3
move 1 from 6 to 7
move 2 from 9 to 4
move 1 from 9 to 6
move 1 from 9 to 4
move 10 from 4 to 3
move 1 from 1 to 2
move 2 from 5 to 4
move 27 from 3 to 8
move 5 from 3 to 9`