mirror of https://github.com/tLDP/LDP
66 lines
2.2 KiB
Bash
66 lines
2.2 KiB
Bash
#!/bin/bash
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# insertion-sort.bash: Insertion sort implementation in Bash
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# Heavy use of Bash array features:
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#+ (string) slicing, merging, etc
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# URL: http://www.lugmen.org.ar/~jjo/jjotip/insertion-sort.bash.d
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#+ /insertion-sort.bash.sh
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#
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# Author: JuanJo Ciarlante <jjo@irrigacion.gov.ar>
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# Lightly reformatted by ABS Guide author.
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# License: GPLv2
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# Used in ABS Guide with author's permission (thanks!).
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#
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# Test with: ./insertion-sort.bash -t
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# Or: bash insertion-sort.bash -t
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# The following *doesn't* work:
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# sh insertion-sort.bash -t
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# Why not? Hint: which Bash-specific features are disabled
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#+ when running a script by 'sh script.sh'?
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#
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: ${DEBUG:=0} # Debug, override with: DEBUG=1 ./scriptname . . .
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# Parameter substitution -- set DEBUG to 0 if not previously set.
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# Global array: "list"
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typeset -a list
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# Load whitespace-separated numbers from stdin.
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if [ "$1" = "-t" ]; then
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DEBUG=1
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read -a list < <( od -Ad -w24 -t u2 /dev/urandom ) # Random list.
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# ^ ^ process substition
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else
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read -a list
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fi
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numelem=${#list[*]}
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# Shows the list, marking the element whose index is $1
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#+ by surrounding it with the two chars passed as $2.
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# Whole line prefixed with $3.
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showlist()
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{
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echo "$3"${list[@]:0:$1} ${2:0:1}${list[$1]}${2:1:1} ${list[@]:$1+1};
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}
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# Loop _pivot_ -- from second element to end of list.
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for(( i=1; i<numelem; i++ )) do
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((DEBUG))&&showlist i "[]" " "
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# From current _pivot_, back to first element.
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for(( j=i; j; j-- )) do
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# Search for the 1st elem. less than current "pivot" . . .
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[[ "${list[j-1]}" -le "${list[i]}" ]] && break
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done
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(( i==j )) && continue ## No insertion was needed for this element.
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# . . . Move list[i] (pivot) to the left of list[j]:
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list=(${list[@]:0:j} ${list[i]} ${list[j]}\
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# {0,j-1} {i} {j}
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${list[@]:j+1:i-(j+1)} ${list[@]:i+1})
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# {j+1,i-1} {i+1,last}
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((DEBUG))&&showlist j "<>" "*"
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done
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echo
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echo "------"
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echo $'Result:\n'${list[@]}
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exit $?
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