// #define Day9
#if Day9
var linesSplit = File.ReadAllLines("day9/input")
    .ToList();

long sum = 0;
for (int row = 0; row < linesSplit.Count; row++) {
    for (int col = 0; col < linesSplit[row].Length; col++) {
        sum += Check(linesSplit, row, col, int.Parse(linesSplit[row][col].ToString()));
    }
}

Console.WriteLine(sum);

// PartTwo
List<long> basinSizes = new List<long>();
for (int row = 0; row < linesSplit.Count; row++) {
    for (int col = 0; col < linesSplit[row].Length; col++) {
        if (Check(linesSplit, row, col, int.Parse(linesSplit[row][col].ToString())) > 0) {
            var cur = new Point(row, col, int.Parse(linesSplit[row][col].ToString()));
            var inBasin = Basin(linesSplit, cur, new HashSet<Point>() {cur});
            basinSizes.Add(inBasin.Count);
        }
    }
}

var res = basinSizes.OrderByDescending(x => x).Take(3).Aggregate(1L, (x, y) => x * y);
Console.WriteLine(res);

HashSet<Point> Basin(List<string> map, Point cur, HashSet<Point> visited) {
    if (cur.row > 0) {
        var above = new Point(cur.row-1, cur.col, int.Parse(map[cur.row-1][cur.col].ToString()));
        if (above.value != 9 && cur.value < above.value && !visited.Contains(above)) {
            var newVisited = new HashSet<Point>(visited);
            newVisited.Add(above);
            visited = Basin(linesSplit, above, newVisited);
        }
    }
    if (cur.row < map.Count-1) {
        var above = new Point(cur.row+1, cur.col, int.Parse(map[cur.row+1][cur.col].ToString()));
        if (above.value != 9 && cur.value < above.value && !visited.Contains(above)) {
            var newVisited = new HashSet<Point>(visited);
            newVisited.Add(above);
            visited = Basin(linesSplit, above, newVisited);
        }
    }
    if (cur.col < map[cur.row].Length-1) {
        var above = new Point(cur.row, cur.col+1, int.Parse(map[cur.row][cur.col+1].ToString()));
        if (above.value != 9 && cur.value < above.value && !visited.Contains(above)) {
            var newVisited = new HashSet<Point>(visited);
            newVisited.Add(above);
            visited = Basin(linesSplit, above, newVisited);
        }
    }
    if (cur.col >0) {
        var above = new Point(cur.row, cur.col-1, int.Parse(map[cur.row][cur.col-1].ToString()));
        if (above.value != 9 && cur.value < above.value && !visited.Contains(above)) {
            var newVisited = new HashSet<Point>(visited);
            newVisited.Add(above);
            visited = Basin(linesSplit, above, newVisited);
        }
    }

    return visited;
}

int Check(List<string> map, int row, int col, int value) {
    if (row > 0) {
        if (value >= int.Parse(map[row-1][col].ToString())) {
            return 0;
        }
    }
    if (row < map.Count-1) {
        if (value >= int.Parse(map[row+1][col].ToString())) {
            return 0;
        }
    }
    if (col < map[row].Length - 1) {
        if (value >= int.Parse(map[row][col+1].ToString())) {
            return 0;
        }
    }
    if (col > 0) {
        if (value >= int.Parse(map[row][col-1].ToString())) {
            return 0;
        }
    }

    return 1 + value;
}

record Point(int row, int col, int value);
#endif