dont list files in the mentioned directories - bash

Question

I have three directories with sub directories the parent directory are a, b, & c. a1&a2 are subdirectories of a, b1&b2 are subdirectories of b, c1&c2 are subdirectories of c. The files are arranged like this format a.txt(a), a1.txt(a1), a2.txt(a2), b.txt(b), b1.txt(b1), b2.txt(b2), c.txt(c), c1.txt(c1), c2.txt(c2). Now I am trying to list the files like i want to ignore the files in the entire directory a with its sub directories a1&a2 and want to igonre the files only in the directory b1 not directory b or b2 and want to ignore the files only in the directory c2 not the directories c or c1. Script which I have tried is below
#!/bin/sh
find * -type d | while IFS= read d
do
dirname=`basename $d`
if [ ${dirname} != "a" ] || [ ${dirname} != "b1" ] || [ ${dirname} != "c2" ]
then
cd $dirname
find * ! -name . -prune -type f | while read fname
do
fname=`basename $fname`
echo $fname
done
fi
done
The results are of the above script is
a.txt
a2.txt
b.sh: a1: does not exist
May i know what is the mistake i am doing in it.

Answer 1

To reproduce test
mkdir -p {a/a,b/b,c/c}{1,2}
touch {a/a,b/b,c/c}.txt
for d in {a/a,b/b,c/c}{1,2}; do touch $d/${d#*/}.txt; done
find . -type f
./a/a.txt
./a/a1/a1.txt
./a/a2/a2.txt
./b/b.txt
./b/b1/b1.txt
./b/b2/b2.txt
./c/c.txt
./c/c1/c1.txt
./c/c2/c2.txt
The find command
find . \( -path ./a -o -path ./b/b1 -o -path ./c/c2 \) -prune -o -print
Explanation
-prune over a directory will prevent find to descend into it, is applied over condition between escaped parenthesis -o equivalent to -or, however it returns true on matching files, after the next -o conditions can be added, (by default junction is -a, -and which can be ommited) and action (-printf -ls -exec etc.).
Other example :
find . \( -path ./a -o -path ./b/b1 -o -path ./c/c2 \) -prune -type f -o -type f
./b/b.txt
./b/b2/b2.txt
./c/c.txt
./c/c1/c1.txt
EDIT after comment:
find . -type d \( -name a -o -name b1 -o -name c2 \) -prune -type f -o -type f -printf '%f\n'
b.txt
b2.txt
c.txt
c1.txt
EDIT after last comment (SunOS find doesn't have -printf) :
find . -type d \( -name a -o -name b1 -o -name c2 \) -prune -o -type f -exec sh -c 'for f; do d=${f%/*}; echo "${d##*/}" "${f##*/}"; done' sh-echo {} +
b b.txt
b2 b2.txt
c c.txt
c1 c1.txt