Solutions for week 140, part 1.

34 files changed, 906 insertions, 1 deletions

diff --git a/challenge-140/abigail/README.md b/challenge-140/abigail/README.md
index bb2b1dda43..0707d1fbd5 100644
--- a/challenge-140/abigail/README.md
+++ b/challenge-140/abigail/README.md
@@ -6,7 +6,6 @@
 * [Bash](bash/ch-1.sh)
 * [Bc](bc/ch-1.bc)
 * [C](c/ch-1.c)
-* [Erlang](c/ch-1.erl)
 * [Go](go/ch-1.go)
 * [Java](java/ch-1.java)
 * [Lua](lua/ch-1.lua)
diff --git a/challenge-140/abigail/awk/ch-1.awk b/challenge-140/abigail/awk/ch-1.awk
new file mode 100644
index 0000000000..3210e7b108
--- /dev/null
+++ b/challenge-140/abigail/awk/ch-1.awk
@@ -0,0 +1,38 @@
+#!/usr/bin/awk
+
+#
+# See ../README.md
+#
+
+#
+# Run as: awk -f ch-1.awk < input-file
+#
+
+#
+# Take a binary representation, return its decimal equivalent
+#
+function bin2dec (bin, dec, digits, n) {
+    dec = 0
+    n = split (bin, digits, "")
+    for (i = 1; i <= n; i ++) {
+        dec = 2 * dec + digits [i]
+    }
+    return (dec)
+}
+
+
+#
+# Get a binary representation
+#
+function dec2bin (dec, bin) {
+    while (dec) {
+        bin = dec % 2 bin
+        dec = int (dec / 2)
+    }
+    return (bin)
+}
+
+
+{
+    print dec2bin(bin2dec($1) + bin2dec($2))
+}
diff --git a/challenge-140/abigail/awk/ch-2.awk b/challenge-140/abigail/awk/ch-2.awk
new file mode 100644
index 0000000000..32372950cc
--- /dev/null
+++ b/challenge-140/abigail/awk/ch-2.awk
@@ -0,0 +1,29 @@
+#!/usr/bin/awk
+
+#
+# See ../README.md
+#
+
+#
+# Run as: awk -f ch-2.awk < input-file
+#
+
+{
+    i = $1
+    j = $2
+    k = $3
+
+    n = 0
+    while (k > 0) {
+        n ++
+        s = int (sqrt (n))
+        for (d = 1; d <= s && k > 0; d ++) {
+            if (!(n % d)) {
+                k -= (d <= i && n / d <= j) + \
+                     (d <= j && n / d <= i) - (n == d * d)
+            }
+        }
+    }
+    print (n)
+}
+
diff --git a/challenge-140/abigail/bash/ch-1.sh b/challenge-140/abigail/bash/ch-1.sh
new file mode 100644
index 0000000000..24b57c5079
--- /dev/null
+++ b/challenge-140/abigail/bash/ch-1.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+
+#
+# See ../README.md
+#
+
+#
+# Run as: bash ch-1.sh < input-file
+#
+
+#
+# Take a binary representation, return its decimal equivalent
+#
+function bin2dec () {
+    local bin=$1
+    local i
+    ((dec = 0))
+    for ((i = 0; i < ${#bin}; i ++)) {
+        ((dec = 2 * dec + ${bin:$i:1}))
+    }
+}
+
+#
+# Given a decimal number, return its binary representation
+#
+function dec2bin () {
+    local dec=$1
+    bin=""
+    while ((dec > 0))
+    do    bin=$((dec % 2))$bin
+          ((dec /= 2))
+    done
+}
+
+set -f
+
+while read a b
+do    bin2dec $a; a=$dec
+      bin2dec $b; b=$dec
+      dec2bin $((a + b))
+      echo $bin
+done
diff --git a/challenge-140/abigail/bash/ch-2.sh b/challenge-140/abigail/bash/ch-2.sh
new file mode 100644
index 0000000000..16757fccb3
--- /dev/null
+++ b/challenge-140/abigail/bash/ch-2.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+
+#
+# See ../README.md
+#
+
+#
+# Run as: bash ch-2.sh < input-file
+#
+
+set -f
+
+while read i j k
+do    ((n = 0))
+      while ((k > 0))
+      do ((n ++))
+         for ((d = 1; d * d <= n && k > 0; d ++))
+         do  if   ((n % d == 0))
+             then if   ((d <= i && n / d <= j))
+                  then ((k --))
+                  fi
+                  if   ((d <= j && n / d <= i))
+                  then ((k --))
+                  fi
+                  if   ((n == d * d))
+                  then ((k ++))
+                  fi
+             fi
+         done
+     done
+     echo $n
+done
diff --git a/challenge-140/abigail/bc/ch-1.bc b/challenge-140/abigail/bc/ch-1.bc
new file mode 100644
index 0000000000..9e1fe422ad
--- /dev/null
+++ b/challenge-140/abigail/bc/ch-1.bc
@@ -0,0 +1,18 @@
+#
+# See ../README.md
+#
+
+#
+# Run as: bc ch-1.bc < input-file
+#
+
+obase=2
+ibase=2
+
+while (1) {
+    a = read(); if (a == 0) {break}
+    b = read(); if (b == 0) {break}
+    a + b
+}
+
+quit
diff --git a/challenge-140/abigail/bc/ch-2.bc b/challenge-140/abigail/bc/ch-2.bc
new file mode 100644
index 0000000000..bb4f56c509
--- /dev/null
+++ b/challenge-140/abigail/bc/ch-2.bc
@@ -0,0 +1,29 @@
+#
+# See ../README.md
+#
+
+#
+# Run as: bc ch-2.bc < input-file
+#
+
+while (1) {
+    i = read (); if (i == 0) {break}
+    j = read (); if (j == 0) {break}
+    k = read (); if (k == 0) {break}
+
+    n = 0
+    while (k > 0) {
+        n = n + 1
+        for (d = 1; d * d <= n && k > 0; d ++) {
+            if (n % d == 0) {
+                if (d <= i && n / d <= j) {k = k - 1}
+                if (d <= j && n / d <= i) {k = k - 1}
+                if (n == d * d)           {k = k + 1}
+            }
+        }
+    }
+
+    n
+}
+
+quit
diff --git a/challenge-140/abigail/c/ch-1.c b/challenge-140/abigail/c/ch-1.c
new file mode 100644
index 0000000000..6c9024bda9
--- /dev/null
+++ b/challenge-140/abigail/c/ch-1.c
@@ -0,0 +1,62 @@
+# include <stdlib.h>
+# include <stdio.h>
+# include <string.h>
+
+/*
+ * See ../README.md
+ */
+
+/*
+ * Run as: cc -o ch-1.o ch-1.c; ./ch-1.o < input-file
+ */
+
+/*
+ * Given a decimal number, return its binary representation
+ */
+char * dec2bin (long dec) {
+    char * bin;
+    if ((bin = (char *) malloc (32 * sizeof (char))) == NULL) {
+        perror ("Malloc failed");
+        exit (1);
+    }
+    if (dec == 0) {     /* Special case dec == 0 */
+        bin [0] =  '0';
+        bin [1] = '\0';
+        return (bin);
+    }
+    size_t i =  0;
+    while (dec) {
+        bin [i ++] = '0' + dec % 2;
+        dec /= 2;
+    }
+    /*
+     * Reverse the string
+     */
+    for (size_t j = 0; j < i / 2; j ++) {
+        char t = bin [j];
+        bin [j] = bin [i - j - 1];
+        bin [i - j - 1] = t;
+    }
+
+    bin [i] = '\0';
+    return (bin);
+}
+
+
+int main (void) {
+    char *  line    = NULL;
+    size_t  len     = 0;
+    size_t  str_len;
+
+    while ((str_len = getline (&line, &len, stdin)) != -1) {
+        char * end_ptr;
+        long a = strtol (line, &end_ptr, 2);
+        long b = strtol (end_ptr,  NULL, 2);
+        char * bin = dec2bin (a + b);
+        printf ("%s\n", bin);
+        free (bin);
+    }
+    free (line);
+
+    return (0);
+}
diff --git a/challenge-140/abigail/c/ch-2.c b/challenge-140/abigail/c/ch-2.c
new file mode 100644
index 0000000000..b57fb1d955
--- /dev/null
+++ b/challenge-140/abigail/c/ch-2.c
@@ -0,0 +1,39 @@
+# include <stdlib.h>
+# include <stdio.h>
+# include <string.h>
+# include <math.h>
+
+/*
+ * See ../README.md
+ */
+
+/*
+ * Run as: cc -o ch-2.o ch-2.c; ./ch-2.o < input-file
+ */
+
+int main (void) {
+    long i, j;
+    long long k;
+
+    while (scanf ("%ld%ld%lld", &i, &j, &k) == 3) {
+        long long n = 0;
+        while (k > 0) {
+            long s = lrintf (sqrt (++ n));
+            for (long d = 1; d <= s && k > 0; d ++) {
+                /*
+                 * Subtract the number of divisors d, where d <= i,
+                 * and n / d <= j, or d <= j and n / d <= i.
+                 * A number d is a divisor if n % d == 0.
+                 * We should count a divisor only once if n == d * d.
+                 */
+                if (!(n % d)) {
+                    k -= (d <= i && n / d <= j) +
+                         (d <= j && n / d <= i) - (n == d * d);
+                }
+            }
+        }
+        printf ("%lld\n", n);
+    }
+
+    return (0);
+}
diff --git a/challenge-140/abigail/go/ch-1.go b/challenge-140/abigail/go/ch-1.go
new file mode 100644
index 0000000000..c355358d16
--- /dev/null
+++ b/challenge-140/abigail/go/ch-1.go
@@ -0,0 +1,32 @@
+package main
+
+//
+// See ../README.md
+//
+
+//
+// Run as: go run ch-1.go
+//
+
+import (
+    "fmt"
+    "bufio"
+    "os"
+    "strconv"
+    "strings"
+)
+
+func main () {
+    var reader = bufio . NewReader (os. Stdin)
+    for {
+        var text, err = reader . ReadString ('\n')
+        if (err != nil) {
+            break
+        }
+        bins := strings . Split (strings . Trim (text, "\n"), " ")
+        a, _ := strconv . ParseInt (bins [0], 2, 0) 
+        b, _ := strconv . ParseInt (bins [1], 2, 0) 
+        
+        fmt . Println (strconv . FormatInt (a + b, 2))
+    }
+}
diff --git a/challenge-140/abigail/go/ch-2.go b/challenge-140/abigail/go/ch-2.go
new file mode 100644
index 0000000000..0f35815237
--- /dev/null
+++ b/challenge-140/abigail/go/ch-2.go
@@ -0,0 +1,37 @@
+package main
+
+//
+// See ../README.md
+//
+
+//
+// Run as: go run ch-2.go < input-file
+//
+
+import (
+    "fmt"
+    "math"
+)
+
+func main () {
+    for {
+        var i, j, k int64
+        c, err := fmt . Scanf ("%d %d %d", &i, &j, &k)
+        if (c != 3 || err != nil) {
+            break;
+        }
+        n := int64 (0)
+        for ;k > 0; {
+            n ++
+            s := int64 (math . Sqrt (float64 (n)))
+            for d := int64 (1); d <= s && k > 0; d ++ {
+                if (n % d == 0) {
+                    if (d <= i && n / d <= j) {k --}
+                    if (d <= j && n / d <= i) {k --}
+                    if (n == d * d)           {k ++}
+                }
+            }
+        }
+        fmt . Println (n)
+    }
+}
diff --git a/challenge-140/abigail/java/ch-1.java b/challenge-140/abigail/java/ch-1.java
new file mode 100644
index 0000000000..7d93af1d7d
--- /dev/null
+++ b/challenge-140/abigail/java/ch-1.java
@@ -0,0 +1,22 @@
+//
+// See ../README.md
+//
+
+//
+// Run as: ln ch-1.java ch1.java; javac ch1.java; java ch1 < input-file
+//
+
+import java.util.*;
+
+public class ch1 {
+    public static void main (String [] args) {
+        Scanner scanner = new Scanner (System . in);
+        while (scanner . hasNextLine ()) {
+            String line = scanner . nextLine ();
+            String [] parts = line . trim () . split (" ");
+            int a = Integer . parseInt (parts [0], 2);
+            int b = Integer . parseInt (parts [1], 2);
+            System . out . println (Integer . toBinaryString (a + b));
+        }
+    }
+}
diff --git a/challenge-140/abigail/java/ch-2.java b/challenge-140/abigail/java/ch-2.java
new file mode 100644
index 0000000000..90c4bd998f
--- /dev/null
+++ b/challenge-140/abigail/java/ch-2.java
@@ -0,0 +1,33 @@
+//
+// See ../README.md
+//
+
+//
+// Run as: ln ch-2.java ch2.java; javac ch2.java; java ch2 < input-file
+//
+
+import java.util.*;
+
+public class ch2 {
+    public static void main (String [] args) {
+        Scanner scanner = new Scanner (System . in);
+        while (scanner . hasNextLong ()) {
+            long i = scanner . nextLong ();
+            long j = scanner . nextLong ();
+            long k = scanner . nextLong ();
+            long n = 0;
+            while (k > 0) {
+                n ++;
+                long s = (long) Math . sqrt (n);
+                for (long d = 1; d <= s && k > 0; d ++) {
+                    if (n % d == 0) {
+                        if (d <= i && n / d <= j) {k --;}
+                        if (d <= j && n / d <= i) {k --;}
+                        if (n == d * d)           {k ++;}
+                    }
+                }
+            }
+            System . out . println (n);
+        }
+    }
+}
diff --git a/challenge-140/abigail/lua/ch-1.lua b/challenge-140/abigail/lua/ch-1.lua
new file mode 100644
index 0000000000..b0ad7ae3fd
--- /dev/null
+++ b/challenge-140/abigail/lua/ch-1.lua
@@ -0,0 +1,28 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-1.lua < input-file
+--
+
+function dec2bin (dec)
+    local bin = {}
+    local out = ""
+    while dec > 0 do
+        bin [#bin + 1] = dec % 2
+        dec = math . floor (dec / 2)
+    end
+    for i = #bin, 1, -1 do
+        out = out .. bin [i]
+    end
+    return out
+end
+
+
+for line in io . lines () do
+    _, _, a, b = line : find ("([01]+)%s+([01]+)")
+    print (dec2bin (tonumber (a, 2) + tonumber (b, 2)))
+end
diff --git a/challenge-140/abigail/lua/ch-2.lua b/challenge-140/abigail/lua/ch-2.lua
new file mode 100644
index 0000000000..601fc35041
--- /dev/null
+++ b/challenge-140/abigail/lua/ch-2.lua
@@ -0,0 +1,30 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-2.lua < input-file
+--
+
+for line in io . lines () do
+    local _, _, i, j, k = line : find ("([0-9]+)%s+([0-9]+)%s+([0-9]+)")
+    i = tonumber (i)
+    j = tonumber (j)
+    k = tonumber (k)
+
+    local n = 0
+    while k > 0 do
+        n = n + 1
+        local s = math . floor (math . sqrt (n))
+        for d = 1, s do
+            if n % d == 0 then
+                if d <= i and n / d <= j then k = k - 1 end
+                if d <= j and n / d <= i then k = k - 1 end
+                if n == d * d            then k = k + 1 end
+            end
+        end
+    end
+    print (n)
+end
diff --git a/challenge-140/abigail/node/ch-1.js b/challenge-140/abigail/node/ch-1.js
new file mode 100644
index 0000000000..18dc51e939
--- /dev/null
+++ b/challenge-140/abigail/node/ch-1.js
@@ -0,0 +1,17 @@
+#!/usr/local/bin/node
+
+//
+// See ../README.md
+//
+
+//
+// Run as: node ch-1.js < input-file
+//
+
+  require ('readline')
+. createInterface ({input: process . stdin})   
+. on              ('line', line => {
+    let [a, b] = line . trim () . split (" ");
+    console . log ((parseInt (a, 2) + parseInt (b, 2)) . toString (2))
+})
+
diff --git a/challenge-140/abigail/node/ch-2.js b/challenge-140/abigail/node/ch-2.js
new file mode 100644
index 0000000000..711c05f7de
--- /dev/null
+++ b/challenge-140/abigail/node/ch-2.js
@@ -0,0 +1,28 @@
+#!/usr/local/bin/node
+
+//
+// See ../README.md
+//
+
+//
+// Run as: node ch-2.js < input-file
+//
+
+  require ('readline')
+. createInterface ({input: process . stdin})   
+. on              ('line', line => {
+    let [i, j, k] = line . split (" ") . map (_ => +_)
+    let n = 0
+    while (k > 0) {
+        n ++
+        let s = Math . floor (Math . sqrt (n))
+        for (let d = 1; d <= s && k > 0; d ++) {
+            if (n % d == 0) {
+                if (d <= i && n / d <= j) {k --}
+                if (d <= j && n / d <= i) {k --}
+                if (n == d * d)           {k ++}
+            }
+        }
+    }
+    console . log (n)
+})
diff --git a/challenge-140/abigail/pascal/ch-1.p b/challenge-140/abigail/pascal/ch-1.p
new file mode 100644
index 0000000000..57e691e9c0
--- /dev/null
+++ b/challenge-140/abigail/pascal/ch-1.p
@@ -0,0 +1,40 @@
+Program ch1;
+
+uses Strutils;
+
+(*                  *)
+(* See ../README.md *)
+(*                  *)
+
+(*                                                        *)
+(* Run as: fpc -och-1.out ch-1.p; ./ch-1.out < input-file *)
+(*                                                        *)
+
+function bin2dec (bin: string): longint;
+    var
+        c: char;
+        dec: integer = 0;
+
+    begin
+        for c in bin do begin
+            dec := dec * 2;
+            if c = '1' then begin
+                dec := dec + 1;
+            end;
+        end;
+        bin2dec := dec;
+    end;
+
+var 
+    n1, n2: longint;
+    a, b: string;
+
+begin
+    while not eof do begin
+        readln (n1, n2);
+        a := Dec2Numb (n1, 1, 10);
+        b := Dec2Numb (n2, 1, 10);
+
+        writeln (Dec2Numb (bin2dec (a) + bin2dec (b), 1, 2));
+    end
+end.
diff --git a/challenge-140/abigail/pascal/ch-2.p b/challenge-140/abigail/pascal/ch-2.p
new file mode 100644
index 0000000000..9eb1661bfc
--- /dev/null
+++ b/challenge-140/abigail/pascal/ch-2.p
@@ -0,0 +1,36 @@
+Program ch2;
+
+(*                  *)
+(* See ../README.md *)
+(*                  *)
+
+(*                                                        *)
+(* Run as: fpc -och-2.out ch-2.p; ./ch-2.out < input-file *)
+(*                                                        *)
+
+uses
+    math;
+
+var
+    i, j, k, n, s, d: longint;
+
+begin
+    while not eof do begin
+        readln (i, j, k);
+
+        n := 0;
+
+        while k > 0 do begin
+            inc (n);
+            s := round (sqrt (n));
+            for d := 1 to s do begin
+                if n mod d = 0 then begin
+                    if (d <= i) and (n / d <= j) then begin dec (k); end;
+                    if (d <= j) and (n / d <= i) then begin dec (k); end;
+                    if (n  = d * d)              then begin inc (k); end;
+                end
+            end
+        end;
+        writeln (n);
+    end
+end.
diff --git a/challenge-140/abigail/python/ch-1.py b/challenge-140/abigail/python/ch-1.py
new file mode 100644
index 0000000000..7002b13c03
--- /dev/null
+++ b/challenge-140/abigail/python/ch-1.py
@@ -0,0 +1,15 @@
+#!/opt/local/bin/python
+
+#
+# See ../README.md
+#
+
+#
+# Run as: python ch-1.py < input-file
+#
+
+import fileinput
+
+for line in fileinput . input ():
+    a, b = line . strip () . split (" ")
+    print (bin (int (a, 2) + int (b, 2)) [2:])
diff --git a/challenge-140/abigail/python/ch-2.py b/challenge-140/abigail/python/ch-2.py
new file mode 100644
index 0000000000..a7bdccbb49
--- /dev/null
+++ b/challenge-140/abigail/python/ch-2.py
@@ -0,0 +1,25 @@
+#!/opt/local/bin/python
+
+#
+# See ../README.md
+#
+
+#
+# Run as: python ch-2.py < input-file
+#
+
+import fileinput
+import math
+
+for line in fileinput . input ():
+    i, j, k = map (lambda x: int (x), line . strip () . split (" "))
+    n = 0
+    while k > 0:
+        n = n + 1
+        s = math . floor (math . sqrt (n))
+        for d in range (1, s + 1):
+            if n % d == 0:
+                if d <= i and n / d <= j: k = k - 1
+                if d <= j and n / d <= i: k = k - 1
+                if n == d * d:            k = k + 1
+    print (n)
diff --git a/challenge-140/abigail/r/ch-1.r b/challenge-140/abigail/r/ch-1.r
new file mode 100644
index 0000000000..10fd49abb3
--- /dev/null
+++ b/challenge-140/abigail/r/ch-1.r
@@ -0,0 +1,22 @@
+#
+# See ../README.md
+#
+
+#
+# Run as: Rscript ch-1.r < input-file
+#
+
+stdin <- file ('stdin', 'r')
+repeat {
+    line <- readLines (stdin, n = 1)
+    if (length (line) == 0) {
+        break
+    }
+    
+    parts <- strsplit (line, " ")
+    a <- strtoi (parts [[1]] [[1]], 2)
+    b <- strtoi (parts [[1]] [[2]], 2)
+
+    cat (as.integer (paste (as.integer (rev (intToBits (a + b))),
+                            collapse = "")), "\n")
+}
diff --git a/challenge-140/abigail/r/ch-2.r b/challenge-140/abigail/r/ch-2.r
new file mode 100644
index 0000000000..a83d05ccce
--- /dev/null
+++ b/challenge-140/abigail/r/ch-2.r
@@ -0,0 +1,33 @@
+#
+# See ../README.md
+#
+
+#
+# Run as: Rscript ch-2.r < input-file
+#
+
+stdin <- file ('stdin', 'r')
+repeat {
+    line <- readLines (stdin, n = 1)
+    if (length (line) == 0) {
+        break
+    }
+    parts <- strsplit (line, " ")
+    list  <- as.numeric (parts [[1]])
+    i     <- list [[1]]
+    j     <- list [[2]]
+    k     <- list [[3]]
+    n     <- 0
+    while (k > 0) {
+        n <- n + 1
+        s <- floor (sqrt (n))
+        for (d in 1 : s) {
+            if (n %% d == 0) {
+                if (d <= i && n / d <= j) {k = k - 1}
+                if (d <= j && n / d <= i) {k = k - 1}
+                if (n == d * d)           {k = k + 1}
+            }
+        }
+    }
+    cat (sprintf ("%d\n", n))
+}
diff --git a/challenge-140/abigail/ruby/ch-1.rb b/challenge-140/abigail/ruby/ch-1.rb
new file mode 100644
index 0000000000..bc95be2323
--- /dev/null
+++ b/challenge-140/abigail/ruby/ch-1.rb
@@ -0,0 +1,15 @@
+#!/usr/bin/ruby
+
+#
+# See ../README.md
+#
+ 
+#
+# Run as: ruby ch-1.rb < input-file
+#
+
+ARGF . each_line do
+    | line |
+    a, b = line . strip() . split (" ")
+    puts (a . to_i(2) + b . to_i(2)) . to_s(2)
+end
diff --git a/challenge-140/abigail/ruby/ch-2.rb b/challenge-140/abigail/ruby/ch-2.rb
new file mode 100644
index 0000000000..fe2f27a992
--- /dev/null
+++ b/challenge-140/abigail/ruby/ch-2.rb
@@ -0,0 +1,27 @@
+#!/usr/bin/ruby
+
+#
+# See ../README.md
+#
+ 
+#
+# Run as: ruby ch-2.rb < input-file
+#
+
+ARGF . each_line do
+    | line |
+    i, j, k = line . strip() . split . map {|x| x . to_i}
+    n = 0
+    while k > 0 do
+        n = n + 1
+        s = Math . sqrt(n) . floor()
+        for d in 1 .. s do
+            if n % d == 0 then
+                if d <= i && n / d <= j then k = k - 1 end
+                if d <= j && n / d <= i then k = k - 1 end
+                if n == d * d           then k = k + 1 end
+            end
+        end
+    end
+    puts (n)
+end
diff --git a/challenge-140/abigail/scheme/ch-1.scm b/challenge-140/abigail/scheme/ch-1.scm
new file mode 100644
index 0000000000..45c7e0fc71
--- /dev/null
+++ b/challenge-140/abigail/scheme/ch-1.scm
@@ -0,0 +1,41 @@
+;;;
+;;; See ../README.md
+;;;
+
+;;;
+;;; Run as: guile --no-auto-compile ch-1.scm
+;;;
+
+(use-modules (ice-9 rdelim))
+(use-modules (srfi  srfi-1))
+
+(define (bin2dec bin) 
+    (define len (string-length bin))
+    (cond ((= len 0) 0)
+          (else (+ (string->number (string-take-right bin 1))
+                   (* 2 (bin2dec   (string-drop-right bin 1)))))))
+
+(define (_dec2bin dec)
+    (cond ((= dec 0) "")
+          (else (string-concatenate
+                   (list (_dec2bin       (floor-quotient dec 2))
+                         (number->string (modulo         dec 2)))))))
+