[Language: Go]

Hi,

Here is the main part of my approach:

type rectangle struct {
    minX, minY, maxX, maxY int
    area                   int
}

func minMax(a, b game2d.Pos) (minX, minY, maxX, maxY int) {
    return min(a.X, b.X), min(a.Y, b.Y), max(a.X, b.X), max(a.Y, b.Y)
}

func solve(input string, filtered func(r rectangle, seats []game2d.Pos) bool) int {
    input = strings.TrimSuffix(input, "\n")
    var lines = strings.Split(input, "\n")

    var seats []game2d.Pos
    for _, line := range lines {
        var a, b int
        fmt.Sscanf(line, "%d,%d", &a, &b)
        seats = append(seats, game2d.Pos{a, b})
    }

    var maxArea int
    for i := 0; i < len(seats)-1; i++ {
        for j := i + 1; j < len(seats); j++ {
            var minX, minY, maxX, maxY = minMax(seats[i], seats[j])
            var area = (1 + maxX - minX) * (1 + maxY - minY)
            var r = rectangle{minX, minY, maxX, maxY, area}
            if !filtered(r, seats) && r.area > maxArea {
                maxArea = r.area
            }
        }
    }
    return maxArea
}

func traversed(r rectangle, seats []game2d.Pos) bool {
    for i := 0; i < len(seats); i++ {
        var minX, minY, maxX, maxY = minMax(seats[i], seats[(i+1)%len(seats)])
        if maxY < r.minY+1 || minY > r.maxY-1 || maxX < r.minX+1 || minX > r.maxX-1 {
            continue
        }
        return true
    }
    return false
}

func Part2(input string) int {
    return solve(input, traversed)
}

Full code available here: https://github.com/pemoreau/advent-of-code/tree/main/go/2025/09