1 files changed, 123 insertions, 0 deletions
diff --git a/2021/04/first.go b/2021/04/first.go
new file mode 100644
index 0000000..ed3942b
--- /dev/null
+++ b/2021/04/first.go
@@ -0,0 +1,123 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type grille struct {
+	lines   [][]int
+	columns [][]int
+}
+
+var (
+	best  = 100000000
+	score = 0
+)
+
+// winning func
+func win(g *grille, n int, iter int) {
+	sum := 0
+	for i := 0; i < 5; i++ {
+		for j := 0; j < len(g.lines[i]); j++ {
+			sum += g.lines[i][j]
+		}
+	}
+	if iter < best {
+		best = iter
+		score = sum * n
+		//fmt.Println(iter, n, score, g)
+	}
+}
+
+func main() {
+	f, err := os.Open("input")
+	if err != nil {
+		log.Fatalf("%+v", err)
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	scanner.Split(bufio.ScanLines)
+
+	scanner.Scan()
+	tirage := make([]int, 0)
+	tirageStr := strings.Split(scanner.Text(), ",")
+	// lets process the tirage
+	for _, v := range tirageStr {
+		n, err := strconv.Atoi(v)
+		if err != nil {
+			log.Fatalf("%+v", err)
+		}
+		tirage = append(tirage, n)
+	}
+
+	for scanner.Scan() {
+		// we just scanned the new line
+		// lets init the grille
+		g := new(grille)
+		g.lines = make([][]int, 5)
+		g.columns = make([][]int, 5)
+		for i := 0; i < 5; i++ {
+			g.lines[i] = make([]int, 5)
+			g.columns[i] = make([]int, 5)
+		}
+		// lets populate the grille
+		for i := 0; i < 5; i++ {
+			scanner.Scan()
+			numbers := strings.Fields(scanner.Text())
+			for j := 0; j < 5; j++ {
+				n, err := strconv.Atoi(numbers[j])
+				if err != nil {
+					log.Fatalf("%+v", err)
+				}
+				g.lines[i][j] = n
+				g.columns[j][i] = n
+			}
+		}
+		// lets process the tirage
+	out:
+		for iter, n := range tirage {
+			if iter >= best {
+				//fmt.Println(iter, n, g)
+				break out
+			}
+			// remove the number
+			for i := 0; i < 5; i++ {
+				for j := 0; j < len(g.lines[i]); j++ {
+					if g.lines[i][j] == n {
+						if len(g.lines[i]) == 1 {
+							g.lines[i] = []int{}
+							win(g, n, iter)
+							break out
+						}
+						if j < len(g.lines[i])-1 {
+							g.lines[i][j] = g.lines[i][len(g.lines[i])-1]
+						}
+						g.lines[i] = g.lines[i][:len(g.lines[i])-1]
+					}
+				}
+			}
+			for i := 0; i < 5; i++ {
+				for j := 0; j < len(g.columns[i]); j++ {
+					if g.columns[i][j] == n {
+						if len(g.columns[i]) == 1 {
+							g.columns[i] = []int{}
+							win(g, n, iter)
+							break out
+						}
+						if j < len(g.columns[i])-1 {
+							g.columns[i][j] = g.columns[i][len(g.columns[i])-1]
+						}
+						g.columns[i] = g.columns[i][:len(g.columns[i])-1]
+					}
+				}
+			}
+		}
+	}
+	fmt.Println(score)
+}