Day 5: If You Give a Seed a Fertilizer


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FAQ


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  • kartoffelsaft@programming.dev
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    edit-2
    11 months ago

    Odin

    When I read the problem description I expected the input to also be 2 digit numbers. When I looked at it I just had to say “huh.”

    Second part I think you definitely have to do in reverse (edit: if you are doing a linear search for the answer), as that allows you to nope out as soon as you find a match, whereas with doing it forward you have to keep checking just in case.

    Formatted code

    package day5
    
    import "core:fmt"
    import "core:strings"
    import "core:slice"
    import "core:strconv"
    
    Range :: struct {
        dest: int,
        src: int,
        range: int,
    }
    
    Mapper :: struct {
        ranges: []Range,
    }
    
    parse_range :: proc(s: string) -> (ret: Range) {
        rest := s
    
        parseLen := -1
    
        destOk: bool
        ret.dest, destOk = strconv.parse_int(rest, 10, &parseLen)
        rest = strings.trim_left_space(rest[parseLen:])
    
        srcOk: bool
        ret.src, srcOk = strconv.parse_int(rest, 10, &parseLen)
        rest = strings.trim_left_space(rest[parseLen:])
    
        rangeOk: bool
        ret.range, rangeOk = strconv.parse_int(rest, 10, &parseLen)
    
        return
    }
    
    parse_mapper :: proc(ss: []string) -> (ret: Mapper) {
        ret.ranges = make([]Range, len(ss)-1)
        for s, i in ss[1:] {
            ret.ranges[i] = parse_range(s)
        }
    
        return
    }
    
    parse_mappers :: proc(ss: []string) -> []Mapper {
        mapsStr := make([dynamic][]string)
        defer delete(mapsStr)
    
        restOfLines := ss
        isLineEmpty :: proc(s: string)->bool {return len(s)==0}
    
        for i, found := slice.linear_search_proc(restOfLines, isLineEmpty); 
            found; 
            i, found  = slice.linear_search_proc(restOfLines, isLineEmpty) {
            
            append(&mapsStr, restOfLines[:i])
            restOfLines = restOfLines[i+1:]
        }
        append(&mapsStr, restOfLines[:])
    
        return slice.mapper(mapsStr[1:], parse_mapper)
    }
    
    apply_mapper :: proc(mapper: Mapper, num: int) -> int {
        for r in mapper.ranges {
            if num >= r.src && num - r.src < r.range do return num - r.src + r.dest
        }
    
        return num
    }
    
    p1 :: proc(input: []string) {
        maps := parse_mappers(input)
        defer {
            for m in maps do delete(m.ranges)
            delete(maps)
        }
    
        restSeeds := input[0][len("seeds: "):]
        min := 0x7fffffff
    
        for len(restSeeds) > 0 {
            seedLen := -1
            seed, seedOk := strconv.parse_int(restSeeds, 10, &seedLen)
            restSeeds = strings.trim_left_space(restSeeds[seedLen:])
    
            fmt.print(seed)
            for m in maps {
                seed = apply_mapper(m, seed)
                fmt.print(" ->", seed)
            }
            fmt.println()
    
            if seed < min do min = seed
        }
    
        fmt.println(min)
    }
    
    apply_mapper_reverse :: proc(mapper: Mapper, num: int) -> int {
        for r in mapper.ranges {
            if num >= r.dest && num - r.dest < r.range do return num - r.dest + r.src
        }
    
        return num
    }
    
    p2 :: proc(input: []string) {
        SeedRange :: struct {
            start: int,
            len: int,
        }
    
        seeds := make([dynamic]SeedRange)
        restSeeds := input[0][len("seeds: "):]
    
        for len(restSeeds) > 0 {
            seedLen := -1
            seedS, seedSOk := strconv.parse_int(restSeeds, 10, &seedLen)
            restSeeds = strings.trim_left_space(restSeeds[seedLen:])
    
            seedL, seedLOk := strconv.parse_int(restSeeds, 10, &seedLen)
            restSeeds = strings.trim_left_space(restSeeds[seedLen:])
    
            append(&seeds, SeedRange{seedS, seedL})
        }
    
        maps := parse_mappers(input)
        defer {
            for m in maps do delete(m.ranges)
            delete(maps)
        }
    
        for i := 0; true; i += 1 {
            rseed := i
            #reverse for m in maps {
                rseed = apply_mapper_reverse(m, rseed)
            }
    
            found := false
            for sr in seeds {
                if rseed >= sr.start && rseed < sr.start + sr.len {
                    found = true
                    break
                }
            }
            if found {
                fmt.println(i)
                break
            }
        }
    }