day04/get_valid_passwords.sh

   1 #!/bin/bash
   2
   3 filename=${1:-input.txt}
   4 exec 3<"${filename}"
   5
   6 read -u 3 line
   7
   8 start_password=${line%-*}
   9 end_password=${line#*-}
  10
  11 check_valid_1() {
  12     cur_password=$1
  13     last_val=${cur_password:0:1}
  14     got_dupe=0
  15     if [ $cur_password -ge $start_password ] && [ $cur_password -le $end_password ]; then
  16         for (( a=1; a<${#cur_password}; a++ )); do
  17             val=${cur_password:$a:1}
  18             if [ $val -ge $last_val ]; then
  19                 if [ $val -eq $last_val ]; then
  20                     got_dupe=1
  21                 fi
  22             else
  23                 return 1
  24             fi
  25             last_val=$val
  26         done
  27         if [ $got_dupe -eq 1 ]; then
  28             return 0
  29         fi
  30     else
  31         return 1
  32     fi
  33
  34     return 1
  35 }
  36
  37 check_valid_2() {
  38     cur_password=$1
  39     last_val=${cur_password:0:1}
  40     val=$last_val
  41     dupe_count=1
  42     got_dupe=0
  43     if [ $cur_password -ge $start_password ] && [ $cur_password -le $end_password ]; then
  44         for (( a=1; a<${#cur_password}; a++ )); do
  45             val=${cur_password:$a:1}
  46             if [ $val -ge $last_val ]; then
  47                 if [ $val -eq $last_val ]; then
  48                     dupe_count=$((dupe_count+1))
  49                 else
  50                     # only pairs
  51                     if [ $dupe_count -eq 2 ]; then
  52                         got_dupe=1
  53                     fi
  54                     dupe_count=1
  55                 fi
  56             else
  57                 return 1
  58             fi
  59             last_val=$val
  60         done
  61         if [ $dupe_count -eq 2 ]; then
  62             got_dupe=1
  63         fi
  64         if [ $got_dupe -eq 1 ]; then
  65             return 0
  66         else
  67             return 1
  68         fi
  69     else
  70         return 1
  71     fi
  72
  73     return 1
  74 }
  75
  76 get_next() {
  77     password=$1
  78     temp_password=$((password+1))
  79     last_val=${temp_password:0:1}
  80     new_password="$last_val"
  81     for (( a=1; a<${#temp_password}; a++ )); do
  82         val=${temp_password:$a:1}
  83         if [ $val -lt $last_val ]; then
  84             val=$last_val
  85             for (( b=$a; b<${#temp_password}; b++ )); do
  86                 new_password+=$val
  87             done
  88             echo "$new_password"
  89             return 0
  90         fi
  91         new_password+=$val
  92         last_val=$val
  93     done
  94
  95     echo "$new_password"
  96 }
  97
  98 cur_password=$start_password
  99 valid_passwords=0
 100 valid_passwords_2=0
 101 while [ $cur_password -le $end_password ]; do
 102     #echo -n "$cur_password: "
 103     if ( check_valid_1 $cur_password ); then
 104         #echo -n valid
 105         valid_passwords=$((valid_passwords+1))
 106         if ( check_valid_2 $cur_password ); then
 107             #echo " valid"
 108             valid_passwords_2=$((valid_passwords_2+1))
 109         else
 110             #echo " invalid"
 111             true
 112         fi
 113     else
 114         #echo invalid
 115         true
 116     fi
 117     cur_password=$(get_next $cur_password)
 118 done
 119
 120 echo "There are $valid_passwords valid passwords"
 121 echo "And $valid_passwords_2 really valid passwords"