From a1264d825b6a28a8620a1ee67564bfa0483594dc Mon Sep 17 00:00:00 2001
From: David Ashby <delta.mu.alpha@gmail.com>
Date: Fri, 3 Dec 2021 18:53:09 -0500
Subject: [PATCH] day 3 part 2 finally done, ugly though

---
 03/main.go | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/03/main.go b/03/main.go
index 92b328b..e183b42 100644
--- a/03/main.go
+++ b/03/main.go
@@ -3,7 +3,6 @@ package main
 import (
 	"bufio"
 	"fmt"
-	"math/bits"
 	"os"
 	"strconv"
 	"time"
@@ -39,7 +38,7 @@ func partOne() {
 		line := scanner.Text()
 		lines++
 		n, _ := strconv.ParseInt(line, 2, 64)
-		for i := 0; i < bits.Len(uint(n)); i++ {
+		for i := 0; i < len(line); i++ {
 			// check if the number in the i'th column is 1, then bit-shift back to the 1s place to add it if it is
 			r[i] += (n & (1 << i)) >> i
 		}
@@ -60,7 +59,54 @@ func partOne() {
 func partTwo() {
 	scanner := makeScanner(false)
 
+	var lines int
+	inputs := map[int]int64{}
+	var oxgen, co2scrub int64
+
+	var totalOnes, bitlen int64
 	for scanner.Scan() {
-		// line := scanner.Text()
+		line := scanner.Text()
+		n, _ := strconv.ParseInt(line, 2, 64)
+		inputs[lines] = n
+		bitlen = int64(len(line)) - 1
+		totalOnes += n >> (bitlen)
+		lines++
 	}
+	// make initial check
+	if totalOnes >= int64(lines)/2 {
+		oxgen += (1 << bitlen)
+	} else {
+		co2scrub += (1 << bitlen)
+	}
+
+	for i := bitlen; i > 0; i-- {
+		var oxOnes, oxZeroes, coOnes, coZeroes int64
+		for _, n := range inputs {
+			if oxgen>>i == n>>i {
+				if oxgen>>(i-1)^n>>(i-1) == 1 {
+					oxOnes++
+				} else {
+					oxZeroes++
+				}
+			}
+			if co2scrub>>i == n>>i {
+				if co2scrub>>(i-1)^n>>(i-1) == 1 {
+					coOnes++
+				} else {
+					coZeroes++
+				}
+			}
+		}
+		if oxOnes >= oxZeroes {
+			oxgen += (1 << (i - 1))
+		}
+		if coZeroes == 0 && coOnes != 0 {
+			co2scrub += (1 << (i - 1))
+		} else if coZeroes != 0 && coOnes == 0 {
+			co2scrub += (0 << (i - 1))
+		} else if coOnes < coZeroes {
+			co2scrub += (1 << (i - 1))
+		}
+	}
+	fmt.Println(oxgen * co2scrub)
 }