62 lines
1.1 KiB
Bash
Executable File
62 lines
1.1 KiB
Bash
Executable File
#!/bin/bash
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#
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# ex2.bash: Advent2020 game, day 10/game 2.
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CMD=${0##*/}
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shopt -s extglob
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# quicksort implementation (descending)
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qsort() {
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local pivot i smaller=() larger=()
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qsort_ret=()
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(($#==0)) && return 0
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pivot=$1
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shift
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for i; do
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if (( i > pivot )); then
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smaller+=( "$i" )
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else
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larger+=( "$i" )
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fi
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done
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qsort "${smaller[@]}"
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smaller=( "${qsort_ret[@]}" )
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qsort "${larger[@]}"
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larger=( "${qsort_ret[@]}" )
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qsort_ret=( "${smaller[@]}" "$pivot" "${larger[@]}" )
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}
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declare -a numbers
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readarray -t numbers
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qsort "${numbers[@]}"
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numbers=(${qsort_ret[@]} 0)
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((last=numbers[0]+3))
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numbers=("$last" "${numbers[@]}")
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size=${#numbers[@]}
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declare -a res
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for ((i=1; i<size; ++i)); do
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res[$i]=0
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done
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res[0]=1
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for ((i=0; i<size; ++i)); do
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cur=${numbers[i]}
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r=${res[i]}
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for j in 1 2 3; do
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((next=i+j))
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if ((next < size)); then
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nval=${numbers[next]}
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((diff=cur-nval))
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if ((diff > 0 && diff <= 3)); then
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((res[next]+=r))
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fi
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fi
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done
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done
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printf "%s : size=%d res=%d\n" "$CMD" "$size" "${res[size-1]}"
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exit 0
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