RosettaCodeData/Task/Floyds-triangle/Jq/floyds-triangle-1.jq
2017-09-25 22:28:19 +02:00

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Text

# floyd(n) creates an n-row floyd's triangle
def floyd(n):
def lpad(len): tostring | (((len - length) * " ") + .);
# Construct an array of widths.
# Assuming N is the last integer on the last row (i.e. (n+1)*n/2),
# the last row has n entries from (1+N-n) through N:
def widths:
((n+1)*n/2) as $N
| [range(1 + $N - n; $N + 1) | tostring | length];
# emit line k assuming it starts with the integer "start"
def line(start; k; widths):
reduce range(start; start+k) as $i
(""; . + ($i|lpad(widths[$i - start])) + " ");
widths as $widths
| (reduce range(0;n) as $row
( [0, ""]; # state: i, string
(.[0] + 1) as $i | .[1] as $string
| [ ($i + $row),
($string + "\n" + line($i; $row + 1; $widths )) ] )
| .[1] ) ;