Shell Programming and Scripting

123 45.34
345 67.22
949 36.55
123 94.23
888 22.33
345 32.56

123 45.34
949 36.55
888 22.33
345 32.56

awk '
        {
                if ( A[$1] > $2 || !(A[$1]) )
                        A[$1] = $2
        }
        END {
                for ( k in A )
                        print k, A[k]
        }
' file

( A[$1] > $2 || !(A[$1]) )

( !($1 in A) || A[$1] > $2 )

sort -k1,1 -k2,2n file | awk '!A[$1]++'

my $pre;
while(<DATA>){
	chomp;
	my @arr = split(" ",$_);
	if(exists $hash{$arr[0]} && $hash{$arr[0]}->{'VAL'}>$arr[1]){
		$hash{$arr[0]}->{'VAL'} = $arr[1];
		$hash{$arr[0]}->{'CNT'} = $.;
	}
	elsif(not exists $hash{$arr[0]}){
		$hash{$arr[0]}->{'VAL'} = $arr[1];
		$hash{$arr[0]}->{'CNT'} = $.;
	}
}
for my $key (sort {$hash{$a}->{'CNT'} <=> $hash{$b}->{'CNT'} } keys %hash){
	print $key," ",$hash{$key}->{'VAL'},"\n";
}
__DATA__
123 45.34
345 67.22
949 36.55
123 94.23
888 22.33
345 32.56

dic={}
cnt=0
with open("a.txt") as f:
 for line in f:
  cnt+=1
  line=line.replace("\n","")
  words = line.split(" ")
  key=str(words[0])
  if key in dic:
    if dic[key]['VAL']>words[1]:
      dic[key]['VAL']=words[1]
      dic[key]['CNT']=cnt
  else:
    dic[key]={'VAL':words[1],'CNT':cnt}
for i in sorted(dic.keys(),key=lambda x:dic[x]['CNT']):
 print(i,dic[i]['VAL'])