109 lines
2.3 KiB
Go
109 lines
2.3 KiB
Go
package main
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import (
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"fmt"
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"strings"
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h "git.bullercodeworks.com/brian/adventofcode/helpers"
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)
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var template string
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var insertions map[string]string
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func main() {
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insertions = make(map[string]string)
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inp := h.StdinToStringSlice()
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template = inp[0]
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for i := 2; i < len(inp); i++ {
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pts := strings.Split(inp[i], " -> ")
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insertions[pts[0]] = pts[1]
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}
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part1(template)
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fmt.Println()
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part2(template)
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}
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func transform(inp string) string {
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var ret string
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for i := 0; i < len(inp)-1; i++ {
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pair := inp[i : i+2]
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ret = ret + string(inp[i]) + insertions[pair]
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}
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ret = ret + string(inp[len(inp)-1])
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return ret
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}
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func part1(inp string) {
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for i := 0; i < 10; i++ {
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inp = transform(inp)
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}
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countMap := make(map[byte]int)
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for i := range inp {
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countMap[inp[i]]++
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}
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var mostCommon, leastCommon byte
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mostCount := h.MIN_INT
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leastCount := h.MAX_INT
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for k, v := range countMap {
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if v > mostCount {
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mostCount = v
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mostCommon = k
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}
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if v < leastCount {
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leastCount = v
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leastCommon = k
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}
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}
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fmt.Println("# Part 1")
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fmt.Printf("Most Common: %s (%d)\n", string(mostCommon), mostCount)
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fmt.Printf("Least Common: %s (%d)\n", string(leastCommon), leastCount)
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fmt.Println("Answer", (mostCount - leastCount))
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}
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func part2Transform(pairs map[string]int) map[string]int {
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ret := make(map[string]int)
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for k, v := range pairs {
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add := insertions[k]
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p1, p2 := string(k[0])+add, add+string(k[1])
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ret[p1] += v
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ret[p2] += v
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}
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return ret
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}
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func part2(inp string) {
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// So the obvious way doesn't work for this many steps.
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// Let's try just dealing with pairs.
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pairs := make(map[string]int)
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for i := 0; i < len(inp)-1; i++ {
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pair := inp[i : i+2]
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pairs[pair]++
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}
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for i := 0; i < 40; i++ {
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pairs = part2Transform(pairs)
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}
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countMap := make(map[byte]int)
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for k, v := range pairs {
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countMap[k[0]] = countMap[k[0]] + v
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}
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countMap[inp[len(inp)-1]]++
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var mostCommon, leastCommon byte
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mostCount := h.MIN_INT
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leastCount := h.MAX_INT
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for k, v := range countMap {
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if v > mostCount {
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mostCount = v
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mostCommon = k
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}
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if v < leastCount {
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leastCount = v
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leastCommon = k
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}
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}
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fmt.Println("# Part 2")
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fmt.Printf("Most Common: %s (%d)\n", string(mostCommon), mostCount)
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fmt.Printf("Least Common: %s (%d)\n", string(leastCommon), leastCount)
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fmt.Println("Answer", (mostCount - leastCount))
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}
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