Distinct palindromes within decimal numbers: Difference between revisions
Distinct palindromes within decimal numbers (view source)
Revision as of 05:57, 16 August 2021
, 2 years ago→{{header|jq}}
Thundergnat (talk | contribs) m (Thundergnat moved page Distinct Palindromes Within Decimal Numbers to Distinct Palindromes within decimal numbers: Standardize capitalization) |
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83071934127905179083 true
1320267947849490361205695 false
</pre>
=={{header|jq}}==
'''Works with [[Jq|jq]]''' (but the second task requires a version with support for "big integer" literals)
<br>
'''Works with gojq, the Go implementation of jq''' (provided `keys_unsorted` is replaced by `keys`)
In this entry, except for 0 itself, palindromes involving leading 0s are ignored.
One feature of the implementation given here is that uniqueness is achieved without
any sorting; however, if gojq is used, then `keys` would have to be used, thus entailing a sort after distinctness has been achieved.
Note that for the second task, and for very large integers (greater than 2^53) in general, accurate results require
gojq, or a version of jq supporting "big integer" literals.
<lang jq>
# input: an integer
# output a stream of distinct integers, each representing an admissible palindrome
def palindromes:
# input: an array
def is_palindrome: . == reverse;
def all_palindromes:
(tostring|explode)
| range(0; length) as $i
| range($i+1; length+1) as $j
| .[$i:$j] # candidate
| select(is_palindrome)
| implode
# trim leading 0s:
| if length > 1 then sub("^00*"; "") else . end
| select(length>0) ;
INDEX(all_palindromes; .) | keys_unsorted[] | tonumber;
def task1:
" i palindromes",
(range(100; 126)
| "\(.) \([palindromes]|join(" "))" );
def task2:
(9, 169, 12769, 1238769, 123498769, 12346098769, 1234572098769,
123456832098769, 12345679432098769, 1234567905432098769, 123456790165432098769,
83071934127905179083, 1320267947849490361205695)
| select( any(palindromes; . > 99) );
task1,
"\nThe integers amongst those in the problem statement that have 2 or more digits:",
task2</lang>
{{out}}
<pre>
i palindromes
100 1 0
101 1 101 0
102 1 0 2
103 1 0 3
104 1 0 4
105 1 0 5
106 1 0 6
107 1 0 7
108 1 0 8
109 1 0 9
110 1 11 0
111 1 11 111
112 1 11 2
113 1 11 3
114 1 11 4
115 1 11 5
116 1 11 6
117 1 11 7
118 1 11 8
119 1 11 9
120 1 2 0
121 1 121 2
122 1 2 22
123 1 2 3
124 1 2 4
125 1 2 5
The integers amongst those in the problem statement that have 2 or more digits:
1320267947849490361205695
</pre>
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