Add Perl, Basic, C, C++, Forth, Lua and Python solutions to challenge 097

15 files changed, 722 insertions, 0 deletions

diff --git a/challenge-097/paulo-custodio/basic/ch-1.bas b/challenge-097/paulo-custodio/basic/ch-1.bas
new file mode 100644
index 0000000000..b0110e5f99
--- /dev/null
+++ b/challenge-097/paulo-custodio/basic/ch-1.bas
@@ -0,0 +1,43 @@
+' Challenge 097
+'
+' TASK #1
+'
+' TASK #1 › Caesar Cipher
+' Submitted by: Mohammad S Anwar
+' You are given string $S containing alphabets A..Z only and a number $N.
+'
+' Write a script to encrypt the given string $S using Caesar Cipher with left
+' shift of size $N.
+'
+' Example
+' Input: $S = "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG", $N = 3
+' Output: "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD"
+'
+' Plain:    ABCDEFGHIJKLMNOPQRSTUVWXYZ
+' Cipher:   XYZABCDEFGHIJKLMNOPQRSTUVW
+'
+' Plaintext:  THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
+' Ciphertext: QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD
+
+function caeser(n as integer, text as string) as string
+    dim i as integer, cipher as string
+    dim c as integer
+
+    for i=1 to len(text)
+        if mid(text,i,1)>="A" and mid(text,i,1)<="Z" then
+            c = ((asc(mid(text,i,1))-asc("A")+26-n) mod 26)+asc("A")
+            cipher = cipher & chr(c)
+        else
+            cipher = cipher & mid(text,i,1)
+        end if
+    next i
+    caeser = cipher
+end function
+
+' main
+dim text as string
+dim n as integer, i as integer
+n = val(command(1))
+i = 2: do while command(i)<>"": text = text & command(i) & " ": i=i+1: loop
+
+print caeser(n, text)
diff --git a/challenge-097/paulo-custodio/basic/ch-2.bas b/challenge-097/paulo-custodio/basic/ch-2.bas
new file mode 100644
index 0000000000..fa6bcfbdf9
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+++ b/challenge-097/paulo-custodio/basic/ch-2.bas
@@ -0,0 +1,46 @@
+' Challenge 097
+'
+' TASK #2 › Binary Substings
+' Submitted by: Mohammad S Anwar
+' You are given a binary string $B and an integer $S.
+'
+' Write a script to split the binary string $B of size $S and then find the
+' minimum number of flips required to make it all the same.
+'
+' Example 1:
+' Input: $B = “101100101”, $S = 3
+' Output: 1
+'
+' Binary Substrings:
+'     "101": 0 flip
+'     "100": 1 flip to make it "101"
+'     "101": 0 flip
+' Example 2:
+' Input $B = “10110111”, $S = 4
+' Output: 2
+'
+' Binary Substrings:
+'     "1011": 0 flip
+'     "0111": 2 flips to make it "1011"
+
+function str_flips(a as string, b as string) as integer
+    dim i as integer, flips as integer
+
+    for i=1 to len(a)
+        if mid(a,i,1)<>mid(b,i,1) then flips=flips+1
+    next i
+
+    str_flips=flips
+end function
+
+function bit_flips(bits as string, n as integer) as integer
+    dim i as integer, flips as integer
+
+    for i=n+1 to len(bits) step n
+        flips=flips+str_flips(left(bits,n), mid(bits,i,n))
+    next i
+
+    bit_flips=flips
+end function
+
+print trim(str(bit_flips(command(1), val(command(2)))))
diff --git a/challenge-097/paulo-custodio/c/ch-1.c b/challenge-097/paulo-custodio/c/ch-1.c
new file mode 100644
index 0000000000..7439af95e8
--- /dev/null
+++ b/challenge-097/paulo-custodio/c/ch-1.c
@@ -0,0 +1,58 @@
+/*
+Challenge 097
+
+TASK #1 › Caesar Cipher
+Submitted by: Mohammad S Anwar
+You are given string $S containing alphabets A..Z only and a number $N.
+
+Write a script to encrypt the given string $S using Caesar Cipher with left
+shift of size $N.
+
+Example
+Input: $S = "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG", $N = 3
+Output: "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD"
+
+Plain:    ABCDEFGHIJKLMNOPQRSTUVWXYZ
+Cipher:   XYZABCDEFGHIJKLMNOPQRSTUVW
+
+Plaintext:  THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
+Ciphertext: QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <memory.h>
+#include <ctype.h>
+
+void* check_mem(void* p) {
+    if (!p) {
+        fputs("Out of memory", stderr);
+        exit(EXIT_FAILURE);
+    }
+    return p;
+}
+
+// replace in-place by ciphered text
+void caeser(int n, char* str) {
+    for (int i = 0; i < strlen(str); i++) {
+        if (isalpha(str[i]))
+            str[i] = ((toupper(str[i])-'A'+26-n)%26)+'A';
+    }
+}
+
+int main(int argc, char* argv[]) {
+    char* str = check_mem(strdup(""));
+    if (argc > 2) {
+        int n = atoi(argv[1]);
+        for (int i = 2; i < argc; i++) {
+            str = check_mem(realloc(str, strlen(str)+strlen(argv[i])+2));
+            strcat(str, argv[i]);
+            strcat(str, " ");
+        }
+        str[strlen(str)-1] = '\0';
+        caeser(n, str);
+        printf("%s\n", str);
+    }
+    free(str);
+}
diff --git a/challenge-097/paulo-custodio/c/ch-2.c b/challenge-097/paulo-custodio/c/ch-2.c
new file mode 100644
index 0000000000..d87bfa0547
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+++ b/challenge-097/paulo-custodio/c/ch-2.c
@@ -0,0 +1,51 @@
+/*
+Challenge 097
+
+TASK #2 › Binary Substings
+Submitted by: Mohammad S Anwar
+You are given a binary string $B and an integer $S.
+
+Write a script to split the binary string $B of size $S and then find the
+minimum number of flips required to make it all the same.
+
+Example 1:
+Input: $B = “101100101”, $S = 3
+Output: 1
+
+Binary Substrings:
+    "101": 0 flip
+    "100": 1 flip to make it "101"
+    "101": 0 flip
+Example 2:
+Input $B = “10110111”, $S = 4
+Output: 2
+
+Binary Substrings:
+    "1011": 0 flip
+    "0111": 2 flips to make it "1011"
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int str_flips(const char* a, const char* b, int n) {
+    int flips = 0;
+    for (int i = 0; i < n; i++) {
+        if (a[i] != b[i])
+            flips++;
+    }
+    return flips;
+}
+
+int bit_flips(const char* bits, int n) {
+    int flips = 0;
+    for (int i = n; i < strlen(bits); i += n)
+        flips += str_flips(bits, bits+i, n);
+    return flips;
+}
+
+int main(int argc, char* argv[]) {
+    if (argc == 3)
+        printf("%d\n", bit_flips(argv[1], atoi(argv[2])));
+}
diff --git a/challenge-097/paulo-custodio/cpp/ch-1.cpp b/challenge-097/paulo-custodio/cpp/ch-1.cpp
new file mode 100644
index 0000000000..cddd5df19f
--- /dev/null
+++ b/challenge-097/paulo-custodio/cpp/ch-1.cpp
@@ -0,0 +1,32 @@
+/*
+Challenge 097
+
+TASK #1
+
+*/
+
+#include <iostream>
+#include <string>
+#include <cctype>
+
+// replace in-place by ciphered text
+void caeser(int n, std::string& str) {
+    for (auto& c : str) {
+        if (isalpha(c))
+            c = ((toupper(c)-'A'+26-n)%26)+'A';
+    }
+}
+
+int main(int argc, char* argv[]) {
+    std::string str;
+    if (argc > 2) {
+        int n = atoi(argv[1]);
+        for (int i = 2; i < argc; i++) {
+            str += argv[i];
+            str += " ";
+        }
+        str.pop_back();
+        caeser(n, str);
+        std::cout << str << std::endl;
+    }
+}
diff --git a/challenge-097/paulo-custodio/cpp/ch-2.cpp b/challenge-097/paulo-custodio/cpp/ch-2.cpp
new file mode 100644
index 0000000000..9eff10ac52
--- /dev/null
+++ b/challenge-097/paulo-custodio/cpp/ch-2.cpp
@@ -0,0 +1,50 @@
+/*
+Challenge 097
+
+TASK #2 › Binary Substings
+Submitted by: Mohammad S Anwar
+You are given a binary string $B and an integer $S.
+
+Write a script to split the binary string $B of size $S and then find the
+minimum number of flips required to make it all the same.
+
+Example 1:
+Input: $B = “101100101”, $S = 3
+Output: 1
+
+Binary Substrings:
+    "101": 0 flip
+    "100": 1 flip to make it "101"
+    "101": 0 flip
+Example 2:
+Input $B = “10110111”, $S = 4
+Output: 2
+
+Binary Substrings:
+    "1011": 0 flip
+    "0111": 2 flips to make it "1011"
+*/
+
+#include <iostream>
+#include <string>
+
+int str_flips(const char* a, const char* b, int n) {
+    int flips = 0;
+    for (int i = 0; i < n; i++) {
+        if (a[i] != b[i])
+            flips++;
+    }
+    return flips;
+}
+
+int bit_flips(const std::string& bits, int n) {
+    int flips = 0;
+    for (int i = n; i < static_cast<int>(bits.size()); i += n)
+        flips += str_flips(bits.c_str(), bits.c_str()+i, n);
+    return flips;
+}
+
+int main(int argc, char* argv[]) {
+    if (argc == 3)
+        std::cout << bit_flips(std::string(argv[1]), atoi(argv[2])) << std::endl;
+}
diff --git a/challenge-097/paulo-custodio/forth/ch-1.fs b/challenge-097/paulo-custodio/forth/ch-1.fs
new file mode 100644
index 0000000000..e47986bb41
--- /dev/null
+++ b/challenge-097/paulo-custodio/forth/ch-1.fs
@@ -0,0 +1,48 @@
+#! /usr/bin/env gforth
+
+\ Challenge 097
+\
+\ TASK #1 › Caesar Cipher
+\ Submitted by: Mohammad S Anwar
+\ You are given string $S containing alphabets A..Z only and a number $N.
+\
+\ Write a script to encrypt the given string $S using Caesar Cipher with left
+\ shift of size $N.
+\
+\ Example
+\ Input: $S = "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG", $N = 3
+\ Output: "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD"
+\
+\ Plain:    ABCDEFGHIJKLMNOPQRSTUVWXYZ
+\ Cipher:   XYZABCDEFGHIJKLMNOPQRSTUVW
+\
+\ Plaintext:  THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
+\ Ciphertext: QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD
+
+\ cipher one word
+: caeser    ( n str-addr str-len -- )   \ outputs coded string
+    BOUNDS ?DO
+        I C@ 'A' -                      \ convert to 0..25
+        OVER - 26 + 26 MOD              \ cipher
+        'A' + EMIT                      \ convert back to letter
+    LOOP
+    DROP
+    SPACE
+;
+
+\ get shift value and words from args, cipher each word
+: caeser-args   ( -- )
+    NEXT-ARG DUP 0= IF 1 THROW THEN     \ get first argument
+    S>NUMBER? 0= THROW                  \ convert to number, thow on error
+    DROP                                \ drop high part
+
+    BEGIN NEXT-ARG DUP 0> WHILE         \ for each argument
+        >R >R DUP R> R>                 ( n n addr len )
+        caeser                          \ convert word
+    REPEAT 2DROP
+    DROP
+    CR
+;
+
+caeser-args
+BYE
diff --git a/challenge-097/paulo-custodio/forth/ch-2.fs b/challenge-097/paulo-custodio/forth/ch-2.fs
new file mode 100644
index 0000000000..e19b02f48b
--- /dev/null
+++ b/challenge-097/paulo-custodio/forth/ch-2.fs
@@ -0,0 +1,55 @@
+#! /usr/bin/env gforth
+
+\ Challenge 097
+\
+\ TASK #2 › Binary Substings
+\ Submitted by: Mohammad S Anwar
+\ You are given a binary string $B and an integer $S.
+\
+\ Write a script to split the binary string $B of size $S and then find the
+\ minimum number of flips required to make it all the same.
+\
+\ Example 1:
+\ Input: $B = “101100101”, $S = 3
+\ Output: 1
+\
+\ Binary Substrings:
+\     "101": 0 flip
+\     "100": 1 flip to make it "101"
+\     "101": 0 flip
+\ Example 2:
+\ Input $B = “10110111”, $S = 4
+\ Output: 2
+\
+\ Binary Substrings:
+\     "1011": 0 flip
+\     "0111": 2 flips to make it "1011"
+
+
+\ count number of flipped chars
+: flipped-chars     { str1 str2 len -- count }
+    0               ( count )
+    len 0 ?DO
+        str1 I + C@
+        str2 I + C@
+        <> IF 1+ THEN
+    LOOP
+;
+
+\ count number of flips in sequence
+: flipped-sequence  { str len n -- count }
+    0 str                   ( count cur-str )
+    BEGIN
+        n +                 \ advance to next subtring
+        DUP str len + <
+    WHILE                   \ for each substring
+        str OVER n flipped-chars    ( count str delta )
+        ROT + SWAP                  ( count str )
+    REPEAT DROP
+;
+
+\ main
+NEXT-ARG                            ( str len )
+NEXT-ARG S>NUMBER? 0= THROW DROP    ( str len n )
+flipped-sequence . CR
+BYE
diff --git a/challenge-097/paulo-custodio/lua/ch-1.lua b/challenge-097/paulo-custodio/lua/ch-1.lua
new file mode 100644
index 0000000000..4bb62c085d
--- /dev/null
+++ b/challenge-097/paulo-custodio/lua/ch-1.lua
@@ -0,0 +1,41 @@
+#!/usr/bin/env lua
+
+--[[
+Challenge 097
+
+TASK #1 › Caesar Cipher
+Submitted by: Mohammad S Anwar
+You are given string $S containing alphabets A..Z only and a number $N.
+
+Write a script to encrypt the given string $S using Caesar Cipher with left
+shift of size $N.
+
+Example
+Input: $S = "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG", $N = 3
+Output: "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD"
+
+Plain:    ABCDEFGHIJKLMNOPQRSTUVWXYZ
+Cipher:   XYZABCDEFGHIJKLMNOPQRSTUVW
+
+Plaintext:  THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
+Ciphertext: QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD
+--]]
+
+function caesar(n, text)
+    text = string.upper(text)
+    local cipher = ""
+
+    for i=1, #text do
+        local c = string.sub(text,i,i)
+        if c >= "A" and c <= "Z" then
+            c = string.char((string.byte(c)-string.byte('A')+26-n)%26
+                            +string.byte('A'))
+        end
+        cipher = cipher..c
+    end
+    return cipher
+end
+
+n = arg[1]
+text = ""; for i=2,#arg do text = text..arg[i].." "; end
+io.write(caesar(n, text),"\n")
diff --git a/challenge-097/paulo-custodio/lua/ch-2.lua b/challenge-097/paulo-custodio/lua/ch-2.lua
new file mode 100644
index 0000000000..8157c651ed
--- /dev/null
+++ b/challenge-097/paulo-custodio/lua/ch-2.lua
@@ -0,0 +1,50 @@
+#!/usr/bin/env lua
+
+--[[
+Challenge 097
+
+TASK #2 � Binary Substings
+Submitted by: Mohammad S Anwar
+You are given a binary string $B and an integer $S.
+
+Write a script to split the binary string $B of size $S and then find the
+minimum number of flips required to make it all the same.
+
+Example 1:
+Input: $B = �101100101�, $S = 3
+Output: 1
+
+Binary Substrings:
+    "101": 0 flip
+    "100": 1 flip to make it "101"
+    "101": 0 flip
+Example 2:
+Input $B = �10110111�, $S = 4
+Output: 2
+
+Binary Substrings:
+    "1011": 0 flip
+    "0111": 2 flips to make it "1011"
+--]]
+
+function str_flips(a, b)
+    local flips = 0
+    for i=1,#a do
+        if string.sub(a,i,i) ~= string.sub(b,i,i) then
+            flips = flips+1
+        end
+    end
+    return flips
+end
+
+function bit_flips(bits, n)
+    local flips = 0
+    for i=n+1,#bits,n do
+        flips = flips+str_flips(string.sub(bits,1,1+n-1),
+                                string.sub(bits,i,i+n-1))
+    end
+    return flips
+end
+
+io.write(bit_flips(arg[1], arg[2]),"\n")
+
diff --git a/challenge-097/paulo-custodio/perl/ch-1.pl b/challenge-097/paulo-custodio/perl/ch-1.pl
new file mode 100644
index 0000000000..adf28c1181
--- /dev/null
+++ b/challenge-097/paulo-custodio/perl/ch-1.pl
@@ -0,0 +1,40 @@
+#!/usr/bin/perl
+
+# Challenge 097
+#
+# TASK #1 › Caesar Cipher
+# Submitted by: Mohammad S Anwar
+# You are given string $S containing alphabets A..Z only and a number $N.
+#
+# Write a script to encrypt the given string $S using Caesar Cipher with left
+# shift of size $N.
+#
+# Example
+# Input: $S = "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG", $N = 3
+# Output: "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD"
+#
+# Plain:    ABCDEFGHIJKLMNOPQRSTUVWXYZ
+# Cipher:   XYZABCDEFGHIJKLMNOPQRSTUVW
+#
+# Plaintext:  THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
+# Ciphertext: QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD
+
+use strict;
+use warnings;
+use 5.030;
+
+@ARGV>=2 or die "Usage: ch-1.pl N WORDS...\n";
+my($n, @words) = @ARGV;
+say join " ", caeser($n, @words);
+
+sub caeser {
+    my($n, @words) = @_;
+    my @output;
+    for my $word (@words) {
+        $word =~ s/\W//g;
+        my @codes = map {(ord($_)-ord('A')+26-$n)%26} split //, uc($word);
+        my @cipher = map {chr($_+ord('A'))} @codes;
+        push @output, join "", @cipher;
+    }
+    return @output;
+}
diff --git a/challenge-097/paulo-custodio/perl/ch-2.pl b/challenge-097/paulo-custodio/perl/ch-2.pl
new file mode 100644
index 0000000000..5e4bc9d2f3
--- /dev/null
+++ b/challenge-097/paulo-custodio/perl/ch-2.pl
@@ -0,0 +1,55 @@
+#!/usr/bin/perl
+
+# Challenge 097
+#
+# TASK #2 › Binary Substings
+# Submitted by: Mohammad S Anwar
+# You are given a binary string $B and an integer $S.
+#
+# Write a script to split the binary string $B of size $S and then find the
+# minimum number of flips required to make it all the same.
+#
+# Example 1:
+# Input: $B = “101100101”, $S = 3
+# Output: 1
+#
+# Binary Substrings:
+#     "101": 0 flip
+#     "100": 1 flip to make it "101"
+#     "101": 0 flip
+# Example 2:
+# Input $B = “10110111”, $S = 4
+# Output: 2
+#
+# Binary Substrings:
+#     "1011": 0 flip
+#     "0111": 2 flips to make it "1011"
+
+use strict;
+use warnings;
+use 5.030;
+
+@ARGV==2 && $ARGV[0]=~/^[01]+$/ && $ARGV[1]=~/^\d+$/
+&& length($ARGV[0])%$ARGV[1]==0
+    or die "Usage: ch-2.pl BITS N\n";
+say bit_flips(@ARGV);
+
+sub bit_flips {
+    my($bits, $n) = @_;
+    my $re = "." x $n;
+    my @bits = grep {$_ ne ''} split /($re)/, $bits;
+
+    my $flips = 0;
+    my $b0 = shift @bits;                       # initial value
+    $flips += str_flips($b0, $_) for @bits;     # flips to initial value
+
+    return $flips;
+}
+
+sub str_flips {
+    my($a, $b) = @_;
+    my @a = split //, $a;
+    my @b = split //, $b;
+    my $flips = grep {$a[$_] ne $b[$_]} 0..$#a;
+    return $flips;
+}
diff --git a/challenge-097/paulo-custodio/python/ch-1.py b/challenge-097/paulo-custodio/python/ch-1.py
new file mode 100644
index 0000000000..374dbc9f5f
--- /dev/null
+++ b/challenge-097/paulo-custodio/python/ch-1.py
@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+
+# Challenge 097
+#
+# TASK #1 › Caesar Cipher
+# Submitted by: Mohammad S Anwar
+# You are given string $S containing alphabets A..Z only and a number $N.
+#
+# Write a script to encrypt the given string $S using Caesar Cipher with left
+# shift of size $N.
+#
+# Example
+# Input: $S = "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG", $N = 3
+# Output: "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD"
+#
+# Plain:    ABCDEFGHIJKLMNOPQRSTUVWXYZ
+# Cipher:   XYZABCDEFGHIJKLMNOPQRSTUVW
+#
+# Plaintext:  THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
+# Ciphertext: QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD
+
+import sys
+
+def caeser(n, words):
+    output = []
+    for word in words:
+        codes = [(ord(c)-ord('A')+26-n)%26 for c in word.upper()]
+        cipher = [chr(i+ord('A')) for i in codes]
+        output.append("".join(cipher))
+    return output
+
+n = int(sys.argv[1])
+words = sys.argv[2:]
+print(" ".join(caeser(n, words)))
diff --git a/challenge-097/paulo-custodio/python/ch-2.py b/challenge-097/paulo-custodio/python/ch-2.py
new file mode 100644
index 0000000000..dc0eee00fc
--- /dev/null
+++ b/challenge-097/paulo-custodio/python/ch-2.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+
+# Challenge 097
+#
+# TASK #2 › Binary Substings
+# Submitted by: Mohammad S Anwar
+# You are given a binary string $B and an integer $S.
+#
+# Write a script to split the binary string $B of size $S and then find the
+# minimum number of flips required to make it all the same.
+#
+# Example 1:
+# Input: $B = “101100101”, $S = 3
+# Output: 1
+#
+# Binary Substrings:
+#     "101": 0 flip
+#     "100": 1 flip to make it "101"
+#     "101": 0 flip
+# Example 2:
+# Input $B = “10110111”, $S = 4
+# Output: 2
+#
+# Binary Substrings:
+#     "1011": 0 flip
+#     "0111": 2 flips to make it "1011"
+
+import sys
+import re
+
+def bit_flips(bitstring, n):
+
+    def str_flips(a, b):
+        a = [c for c in a]
+        b = [c for c in b]
+        flips = 0;
+        for i in range(0, len(a)):
+            if a[i] != b[i]:
+                flips += 1
+        return flips
+
+    bits = [bitstring[i:i+n] for i in range(0, len(bitstring), n)]
+    flips = 0
+    for i in range(1, len(bits)):
+        flips += str_flips(bits[0], bits[i])
+    return flips
+
+# main
+assert len(sys.argv) == 3, "Usage: ch-2.py BITS N"
+assert re.match(r"^[01]+$", sys.argv[1]), "BITS must be a bit string"
+assert re.match(r"^\d+$", sys.argv[2]), "N must be a number"
+assert len(sys.argv[1]) % int(sys.argv[2]) == 0, "N must be multiple of size of BITS"
+
+bits, n = sys.argv[1], int(sys.argv[2])
+print(bit_flips(bits,n))
diff --git a/challenge-097/paulo-custodio/test.pl b/challenge-097/paulo-custodio/test.pl
new file mode 100644
index 0000000000..d09b489e04
--- /dev/null
+++ b/challenge-097/paulo-custodio/test.pl
@@ -0,0 +1,64 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use 5.030;
+use Test::More;
+
+# hack so that output redirection works in msys
+my $LUA = $^O eq "msys" ? "lua.exe" : "lua";
+
+run("gcc     c/ch-1.c   -o     c/ch-1");
+run("g++   cpp/ch-1.cpp -o   cpp/ch-1");
+run("fbc basic/ch-1.bas -o basic/ch-1");
+
+for (["THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG"
+   => "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD"]) {
+    my($in, $out) = @$_;
+
+    is capture(     "perl perl/ch-1.pl  3 $in "), "$out\n";
+    is capture(     "perl perl/ch-1.pl -3 $out"), "$in\n";
+    is capture(     "$LUA lua/ch-1.lua  3 $in "), "$out\n";
+    is capture(     "$LUA lua/ch-1.lua -3 $out"), "$in\n";
+    is capture(  "gforth forth/ch-1.fs  3 $in "), "$out\n";
+    is capture(  "gforth forth/ch-1.fs -3 $out"), "$in\n";
+    is capture( "python python/ch-1.py  3 $in "), "$out\n";
+    is capture( "python python/ch-1.py -3 $out"), "$in\n";
+    is capture(             "c/ch-1     3 $in "), "$out\n";
+    is capture(             "c/ch-1    -3 $out"), "$in\n";
+    is capture(           "cpp/ch-1     3 $in "), "$out\n";
+    is capture(           "cpp/ch-1    -3 $out"), "$in\n";
+    is capture(         "basic/ch-1     3 $in "), "$out\n";
+    is capture(         "basic/ch-1    -3 $out"), "$in\n";
+}
+
+run("gcc     c/ch-2.c   -o     c/ch-2");
+run("g++   cpp/ch-2.cpp -o   cpp/ch-2");
+run("fbc basic/ch-2.bas -o basic/ch-2");
+
+for (["101100101 3" => "1"],
+     ["10110111  4" => "2"]) {
+    my($in, $out) = @$_;
+
+    is capture(    "perl perl/ch-2.pl  $in"), "$out\n";
+    is capture(     "$LUA lua/ch-2.lua $in"), "$out\n";
+    is capture( "gforth forth/ch-2.fs  $in"), "$out\n";
+    is capture("python python/ch-2.py  $in"), "$out\n";
+    is capture(            "c/ch-2     $in"), "$out\n";
+    is capture(          "cpp/ch-2     $in"), "$out\n";
+    is capture(        "basic/ch-2     $in"), "$out\n";
+}
+
+done_testing;
+
+sub capture {
+    my($cmd) = @_;
+    my $out = `$cmd`;
+    $out =~ s/[ \r\t]*\n/\n/g;
+    return $out;
+}
+
+sub run {
+    my($cmd) = @_;
+    ok 0==system($cmd), $cmd;
+}