2021: Improvements on days 6 and 7

einarjon · einarjon · commit b25ff15879b6 · 2024-03-07T15:21:54.000Z
diff --git a/2021/06.sh b/2021/06.sh
@@ -1,16 +1,14 @@
 #!/usr/bin/env bash
-A=$(< "${1:-6.txt}")
-A=${A//,}
+declare -i A=(0 0 0 0 0 0 0 0 0) n=0
+while read freq age; do A[age]=$freq; done < <(grep -o [0-9] "${1:-6.txt}" | sort | uniq -c)
 solve() {
-    for ((; n < $1; ++n)); do
-        #births=${A//[^0]}; births=${births//0/8}
-        births=$(tr -cd 0 <<< "$A" | tr 0 8)
-        B=$(echo -n "$A" | tr 876543210 765432106 )
-        A[i]="${B[i]}${births}"
+    while ((n < $1)); do
+        i=$((n++%9))
+        A[i-2]+=${A[i]}
     done
+    sum=0; for i in "${!A[@]}"; do ((sum+=A[i])); done
 }
-n=0
 solve 80
-echo "6A: ${#A}"
-#solve 256
-#echo "6B: ${#A}"
+echo "6A: $sum"
+solve 256
+echo "6B: $sum"
diff --git a/2021/07.sh b/2021/07.sh
@@ -1,20 +1,15 @@
-#!/usr/bin/env bash
-A=($(tr , '\n' < "${1:-7.txt}" | sort -n ))
+#!/bin/bash
+input=$(< ${1:-7.txt})
+A=($(echo -e "${input//,/\\n}" | sort -n))
 MIN=(99999999 0) MIN2=(9999999999999 0)
 N=${#A[@]}
-for ((i=A[N/4]; i<A[-N/4]; i++)); do
-    n=''; for k in ${A[@]};do n+=+$((k-i)); done;
-    sum=$((${n//-})) # lazy abs()
-    ((MIN>sum)) && MIN=($sum $i)
+avg=$(((${input//,/+})/N))
+n=""; for k in ${A[@]};do n+=+$((k-A[N/2])); done
+sum=$((${n//-})) # lazy abs()
+echo "7A: $sum"
+declare -i sum2=0
+for k in ${A[@]}; do
+    dist=$((k-avg)); dist=${dist/-}
+    sum2+=$((dist*(dist+1)/2))
 done
-echo "7A: ${MIN[0]}"
-
-for ((i=A[N/4]; i<A[-N/4]; i++)); do
-    declare -i sum2=0;
-    for k in ${A[@]}; do
-        dist=$((k-i)); dist=${dist/-}
-        sum2+=$((dist*(dist+1)/2))
-    done;
-    ((MIN2>sum2)) && MIN2=($sum2 $i)
-done
-echo "7B: ${MIN2[0]}"
+echo "7B: $sum2"
