2021 Day 4 & Day 5 Complete

2021/day04/main.go

@@ -0,0 +1,197 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	boards := buildBoards(inp[1:])
+	draws := parseDraws(inp[0])
+	//part1(boards, draws)
+	part2(boards, draws)
+}
+
+func part1(boards []Board, draws []int) {
+	var winners []Board
+	for i := range draws {
+		for b := range boards {
+			if boards[b].Mark(draws[i]) {
+				winners = append(winners, boards[b])
+			}
+		}
+		if len(winners) > 0 {
+			break
+		}
+	}
+	for w := range winners {
+		fmt.Println("# Part 1")
+		fmt.Println(winners[w])
+		fmt.Println(winners[w].Score())
+		fmt.Println()
+	}
+}
+
+func part2(boards []Board, draws []int) {
+	var winners []Board
+	for i := range draws {
+		for b := range boards {
+			if boards[b].Mark(draws[i]) {
+				winners = append(winners, boards[b])
+			}
+		}
+		// Remove all winners from boards
+		for i := range winners {
+			for b := range boards {
+				if winners[i].String() == boards[b].String() {
+					boards = append(boards[:b], boards[b+1:]...)
+					break
+				}
+			}
+		}
+
+		if len(boards) == 0 {
+			break
+		}
+	}
+	fmt.Println("# Part 2")
+	fmt.Println("Last Winner")
+	fmt.Println(winners[len(winners)-1])
+	fmt.Println(winners[len(winners)-1].Score())
+	fmt.Println()
+}
+
+func parseDraws(inp string) []int {
+	var ret []int
+	pts := strings.Split(inp, ",")
+	for i := range pts {
+		ret = append(ret, h.Atoi(pts[i]))
+	}
+	return ret
+}
+
+type Spot struct {
+	value  int
+	marked bool
+}
+
+type Board struct {
+	spots map[h.Coordinate]Spot
+	draws []int
+}
+
+func NewBoard(inp []string) Board {
+	b := Board{
+		spots: make(map[h.Coordinate]Spot),
+	}
+	for y := range inp {
+		row := strings.Fields(strings.TrimSpace(inp[y]))
+		for x := range row {
+			v := h.Atoi(row[x])
+			b.spots[h.Coordinate{X: x, Y: y}] = Spot{value: v}
+		}
+	}
+	return b
+}
+
+func buildBoards(inp []string) []Board {
+	var boards []Board
+	var boardStr []string
+	for i := range inp {
+		if inp[i] == "" {
+			// start/end of a board
+			if len(boardStr) == 5 {
+				boards = append(boards, NewBoard(boardStr))
+			}
+			boardStr = []string{}
+		} else {
+			boardStr = append(boardStr, inp[i])
+		}
+	}
+	if len(boardStr) == 5 {
+		boards = append(boards, NewBoard(boardStr))
+	}
+
+	return boards
+}
+
+// Mark adds a number to the draws and returns whether this board has won
+func (b *Board) Mark(v int) bool {
+	b.draws = append(b.draws, v)
+	for k := range b.spots {
+		s := b.spots[k]
+		if b.spots[k].value == v {
+			s.marked = true
+			b.spots[k] = s
+			return b.Won()
+		}
+	}
+	return b.Won()
+}
+
+func (b *Board) Won() bool {
+	for y := 0; y < 5; y++ {
+		if b.CheckRowForWin(y) {
+			return true
+		}
+	}
+	for x := 0; x < 5; x++ {
+		if b.CheckColForWin(x) {
+			return true
+		}
+	}
+	return false
+}
+
+func (b *Board) CheckRowForWin(y int) bool {
+	for x := 0; x < 5; x++ {
+		if b.spots[c(x, y)].marked == false {
+			return false
+		}
+	}
+	return true
+}
+
+func (b *Board) CheckColForWin(x int) bool {
+	for y := 0; y < 5; y++ {
+		if b.spots[c(x, y)].marked == false {
+			return false
+		}
+	}
+	return true
+}
+
+func (b *Board) Score() int {
+	var unmarked int
+	for y := 0; y < 5; y++ {
+		for x := 0; x < 5; x++ {
+			if b.spots[c(x, y)].marked == false {
+				unmarked += b.spots[c(x, y)].value
+			}
+		}
+	}
+	return unmarked * b.draws[len(b.draws)-1]
+}
+
+func (b Board) String() string {
+	var ret string
+	for y := 0; y < 5; y++ {
+		for x := 0; x < 5; x++ {
+			c := c(x, y)
+			marked := " "
+			if b.spots[c].marked {
+				marked = "X"
+			}
+			ret = fmt.Sprintf("%s%s: %2d[%v]  ", ret, c, b.spots[c].value, marked)
+		}
+		ret = ret + "\n"
+	}
+	return ret
+}
+
+func c(x, y int) h.Coordinate {
+	return h.Coordinate{X: x, Y: y}
+}