Combine AoC Repos

2015/day20/main.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+)
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println("Usage: day20 <number>")
+		os.Exit(1)
+	}
+	numPresents := mustAtoi(os.Args[1])
+
+	// 831600 was the lowest for part 1
+	// Part 2 won't be lower, so...
+	// 884520 for Part 2?
+	houseNum := 884500
+	k := receivedPresentsPt2(houseNum)
+	lastFound := houseNum
+	for {
+		houseNum = houseNum + 10
+		k = receivedPresentsPt2(houseNum)
+		if k >= (numPresents / 4 * 3) {
+			fmt.Print("O")
+		} else if k >= numPresents/2 {
+			fmt.Print("o")
+		} else if k >= numPresents/4 {
+			fmt.Print(".")
+		}
+		if k >= numPresents {
+			fmt.Print(" House number " + strconv.Itoa(houseNum) + " received " + strconv.Itoa(k) + " presents.")
+			fmt.Println("(" + strconv.Itoa(lastFound-houseNum) + ")")
+			lastFound = houseNum
+		}
+	}
+	/*
+		for houseNum > 40000 { //k < numPresents {
+			if houseNum%100000 == 0 {
+				fmt.Print("o")
+			} else if houseNum%1000 == 0 {
+				fmt.Print(".")
+			}
+			houseNum = houseNum - 10 //-- // = houseNum - 360
+			k = receivedPresentsPt1(houseNum)
+			if k >= numPresents {
+				fmt.Print(" House number " + strconv.Itoa(houseNum) + " received " + strconv.Itoa(k) + " presents.")
+				fmt.Println("(" + strconv.Itoa(lastFound-houseNum) + ")")
+				lastFound = houseNum
+			}
+		}
+	*/
+}
+
+func receivedPresentsPt2(house int) int {
+	var ret int
+	elves := getFactors(house)
+	for i := range elves {
+		if (house / elves[i]) <= 50 {
+			ret += elves[i] * 11
+		}
+	}
+	return ret
+}
+
+func receivedPresentsPt1(house int) int {
+	var ret int
+	elves := getFactors(house)
+	for i := range elves {
+		ret += elves[i] * 10
+	}
+	return ret
+}
+
+func getFactors(n int) []int {
+	var ret []int
+	bot := 1
+	top := n
+	for bot < n/2 {
+		if n%bot == 0 {
+			top = n / bot
+			if top == bot {
+				ret = addUnique(ret, bot)
+			} else {
+				ret = addUnique(ret, bot)
+				ret = addUnique(ret, top)
+			}
+		}
+		bot++
+	}
+	return ret
+}
+
+func addUnique(sl []int, n int) []int {
+	for i := 0; i < len(sl); i++ {
+		if sl[i] == n {
+			return sl
+		}
+	}
+	return append(sl, n)
+}
+
+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
+}