Combine AoC Repos

2015/day25/main.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+)
+
+func main() {
+	if len(os.Args) < 2 || os.Args[1] == "-help" {
+		fmt.Println("Usage: day25 <row> <col>")
+		fmt.Println("   or: day25 <code number>")
+	}
+	row := mustAtoi(os.Args[1])
+	if len(os.Args) == 2 {
+		fmt.Printf("%d\n", genCodeNum(row))
+		os.Exit(0)
+	}
+	// Must be row/col request
+	col := mustAtoi(os.Args[2])
+	fmt.Printf("%d\n", genCodeNum(codeNumFromRowCol(row, col)))
+}
+
+func codeNumFromRowCol(r int, c int) int {
+	if r == 1 {
+		if c == 1 {
+			return 1
+		}
+		return c + codeNumFromRowCol(r, c-1)
+	}
+	if c == 1 {
+		return codeNumFromRowCol(1, (r-1)) + 1
+	}
+	return codeNumFromRowCol((r+1), (c-1)) + 1
+}
+
+func genCodeNum(i int) int64 {
+	ret := int64(20151125)
+	for i > 1 {
+		ret *= 252533
+		ret = ret % 33554393
+		i--
+	}
+	return ret
+}
+
+func mustAtoi(s string) int {
+	var i int
+	var err error
+	if i, err = strconv.Atoi(s); err != nil {
+		fmt.Println("Tried to atoi " + s)
+		os.Exit(1)
+	}
+	return i
+}