124 lines
2.3 KiB
Go
124 lines
2.3 KiB
Go
package main
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import (
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"bufio"
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"bytes"
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_ "embed"
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"fmt"
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"strconv"
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)
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//go:embed input.txt
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var input []byte
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type partNumber struct {
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number int
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row int
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col int
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end int
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hasSymbol bool
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}
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type symbol struct {
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symbol rune
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row int
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col int
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adjacentParts []*partNumber
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}
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type symbolTab map[int]map[int]*symbol
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func hasSymbol(tab symbolTab, row, col int, p partNumber) bool {
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if cols, ok := tab[row]; ok {
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s, ok := cols[col]
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if ok {
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s.adjacentParts = append(s.adjacentParts, &p)
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cols[col] = s
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}
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return ok
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}
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return false
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}
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func scanSymbol(tab symbolTab, p partNumber) bool {
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rowStart, rowEnd := max(p.row-1, 0), p.row+1
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colStart, colEnd := max(p.col-1, 0), p.end+1
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for i := rowStart; i <= rowEnd; i++ {
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for j := colStart; j <= colEnd; j++ {
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ok := hasSymbol(tab, i, j, p)
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// fmt.Println(p.number, i, j, ok)
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if ok {
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return true
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}
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}
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}
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return false
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}
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func main() {
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buf := bytes.NewReader(input)
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scan := bufio.NewScanner(buf)
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m := [][]rune{}
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parts := []partNumber{}
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symbols := make(symbolTab)
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symbolList := []*symbol{}
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for scan.Scan() {
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text := scan.Text()
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row := len(m)
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m = append(m, []rune(text))
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slice := make([]rune, 0, 3)
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var col int
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for i, a := range text {
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col = i
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if a >= '0' && a <= '9' {
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slice = append(slice, a)
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continue
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}
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if v, err := strconv.Atoi(string(slice)); err == nil {
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parts = append(parts, partNumber{number: v, row: row, col: col - len(slice), end: col - 1})
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slice = slice[:0]
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}
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if a != '.' {
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cols, ok := symbols[row]
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if !ok {
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cols = make(map[int]*symbol)
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}
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s := &symbol{row: row, col: col, symbol: a}
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cols[col] = s
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symbols[row] = cols
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symbolList = append(symbolList, s)
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}
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}
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if v, err := strconv.Atoi(string(slice)); err == nil {
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parts = append(parts, partNumber{number: v, row: row, col: col - len(slice), end: col - 1})
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slice = slice[:0]
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}
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}
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sum := 0
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for i, p := range parts {
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ok := scanSymbol(symbols, p)
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parts[i].hasSymbol = ok
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if ok {
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sum += p.number
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}
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}
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sumGears := 0
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for _, s := range symbolList {
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if s.symbol == '*' && len(s.adjacentParts) == 2 {
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sumGears += s.adjacentParts[0].number * s.adjacentParts[1].number
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}
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}
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fmt.Println(m)
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fmt.Println(parts)
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fmt.Println(symbols)
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fmt.Println(symbolList)
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fmt.Println(sum)
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fmt.Println(sumGears)
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}
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