day04/get_valid_passwords.sh

   1 #!/bin/bash
   2
   3 start_password=254032
   4 end_password=789860
   5
   6 check_valid_1() {
   7     cur_password=$1
   8     last_val=${cur_password:0:1}
   9     val=$last_val
  10     got_dupe=0
  11     if [ $cur_password -ge $start_password ] && [ $cur_password -le $end_password ]; then
  12         for (( a=1; a<${#cur_password}; a++ )); do
  13             val=${cur_password:$a:1}
  14             if [ $val -ge $last_val ]; then
  15                 if [ $val -eq $last_val ]; then
  16                     got_dupe=1
  17                 fi
  18             else
  19                 return 1
  20             fi
  21             last_val=$val
  22         done
  23         if [ $got_dupe -eq 1 ]; then
  24             return 0
  25         fi
  26     else
  27         return 1
  28     fi
  29
  30     return 1
  31 }
  32
  33 check_valid_2() {
  34     cur_password=$1
  35     last_val=${cur_password:0:1}
  36     val=$last_val
  37     dupe_count=1
  38     got_dupe=0
  39     if [ $cur_password -ge $start_password ] && [ $cur_password -le $end_password ]; then
  40         for (( a=1; a<${#cur_password}; a++ )); do
  41             val=${cur_password:$a:1}
  42             if [ $val -ge $last_val ]; then
  43                 if [ $val -eq $last_val ]; then
  44                     dupe_count=$((dupe_count+1))
  45                 else
  46                     # only pairs
  47                     if [ $dupe_count -eq 2 ]; then
  48                         got_dupe=1
  49                     fi
  50                     dupe_count=1
  51                 fi
  52             else
  53                 return 1
  54             fi
  55             last_val=$val
  56         done
  57         if [ $dupe_count -eq 2 ]; then
  58             got_dupe=1
  59         fi
  60         if [ $got_dupe -eq 1 ]; then
  61             return 0
  62         else
  63             return 1
  64         fi
  65     else
  66         return 1
  67     fi
  68
  69     return 1
  70 }
  71
  72 get_next() {
  73     password=$1
  74     temp_password=$((password+1))
  75     last_val=${temp_password:0:1}
  76     new_password="$last_val"
  77     for (( a=1; a<${#temp_password}; a++ )); do
  78         val=${temp_password:$a:1}
  79         if [ $val -lt $last_val ]; then
  80             val=$last_val
  81         fi
  82         new_password+=$val
  83         last_val=$val
  84     done
  85
  86     echo "$new_password"
  87 }
  88
  89 cur_password=$start_password
  90 valid_passwords=0
  91 valid_passwords_2=0
  92 while [ $cur_password -le $end_password ]; do
  93     echo -n "$cur_password: "
  94     if ( check_valid_1 $cur_password ); then
  95         echo -n valid
  96         valid_passwords=$((valid_passwords+1))
  97         if ( check_valid_2 $cur_password ); then
  98             echo " valid"
  99             valid_passwords_2=$((valid_passwords_2+1))
 100         else
 101             echo " invalid"
 102         fi
 103     else
 104         echo invalid
 105     fi
 106     cur_password=$(get_next $cur_password)
 107 done
 108
 109 echo "There are $valid_passwords valid passwords"
 110 echo "And $valid_passwords_2 really valid passwords"