Fractal tree: a solution for a beautiful task from HackerRank (https://www.hackerrank.com/challenges/fractal-trees-all/problem)

trees.py

# same implemented in python as a POC
N=5

print('_' * 100)

offset = 0
for i in range(5-N):
    offset += 2 ** i
    for j in range(2 ** i * 2):
        print('_' * 100)

for i in range(6-N, 6):
    points=2 ** (i - 1)
    cnt = 2 ** (5 - i)
    spc = 2 ** i - 1
    for j in range(points):
        print('_' * 18, end='')
        for k in range(cnt):
            print('_' * offset, end='')
            print('1' + ('_' * spc) + '1', end='')
            print('_' * offset, end='')
            print('_', end='')
        print('_' * 18)
        offset += 1
        spc -= 2
    for j in range(points):
        print('_' * 18, end='')
        for k in range(cnt):
            print('_' * offset, end='')
            print('1', end='')
            print('_' * (offset + 1), end='')
        print('_' * 18)

trees.sh

#! /bin/bash

read N
# N=4

printf '_%.0s' {1..100}
echo

offset=0
for ((i=0; i<5-N; i++)); do
    offset=$((offset + 2 ** i))
    for ((j=0; j<2 ** i * 2; j++)); do
        printf '_%.0s' {1..100}
        echo
    done
done
for ((i=6-N; i<6; i++)); do
    points=$((2 ** (i - 1)))
    cnt=$((2 ** (5-i)))
    spc=$((2 ** i - 1))
    for ((j=0; j<points; j++)); do
        # printf '%2d, %2d, %2d' $points $cnt $j
        printf '_%.0s' {1..18}
        for ((k=0; k<cnt; k++)); do
            if [[ $offset -gt 0 ]]; then
                printf '_%.0s' $(seq 1 $offset)
            fi
            printf '1'
            printf '_%.0s' $(seq 1 $spc)
            printf '1'
            if [[ $offset -gt 0 ]]; then
                printf '_%.0s' $(seq 1 $offset)
            fi
            printf '_'
        done
        printf '_%.0s' {1..18}
        echo
        offset=$((offset + 1))
        spc=$((spc - 2))
    done
    for ((j=0; j<points; j++)); do
        printf '_%.0s' {1..18}
        for ((k=0; k<cnt; k++)); do
            printf '_%.0s' $(seq 1 $offset)
            printf '1'
            printf '_%.0s' $(seq 1 $offset)
            printf '_'
        done
        printf '_%.0s' {1..18}
        echo
    done
done