Solutions from wanderdoc. Happy New Year!

2 files changed, 109 insertions, 0 deletions

diff --git a/challenge-041/wanderdoc/R/ch-01.R b/challenge-041/wanderdoc/R/ch-01.R
new file mode 100644
index 0000000000..36ab135753
--- /dev/null
+++ b/challenge-041/wanderdoc/R/ch-01.R
@@ -0,0 +1,80 @@
+decomp <- function(x)
+{
+  num <- x
+  
+  div_max <-num/2
+  fct<-numeric(0)
+  if(x <=3) {return(fct)} # because of for loop below.
+  
+  for(i in 2:div_max)
+  {
+    while( 0 == x%%i)
+    {
+
+      fct <- c(fct, i) 
+      x = x/i
+    }
+  }
+  fct<-fct[!is.na(fct)]
+}
+
+# https://stackoverflow.com/questions/3789968 , here slightly modified to match 2 too:
+
+isPrime <- function(x)
+{
+  div <- 2:ceiling(sqrt(x))
+
+  !any(x %% div == 0) || 2 == x
+}
+
+print_attractive <- function(x)
+{
+  factors <- decomp(x)
+  size <- length(factors)
+  if(size > 0 && isPrime(size)) 
+     {
+       print(paste(x, paste(factors, collapse=" x "), sep = " = "))
+     }
+}
+
+
+for (i in 1:50)
+{
+  print_attractive(i)
+}
+
+
+
+
+
+# Prints:
+# [1] "4 = 2 x 2"
+# [1] "6 = 2 x 3"
+# [1] "8 = 2 x 2 x 2"
+# [1] "9 = 3 x 3"
+# [1] "10 = 2 x 5"
+# [1] "12 = 2 x 2 x 3"
+# [1] "14 = 2 x 7"
+# [1] "15 = 3 x 5"
+# [1] "18 = 2 x 3 x 3"
+# [1] "20 = 2 x 2 x 5"
+# [1] "21 = 3 x 7"
+# [1] "22 = 2 x 11"
+# [1] "25 = 5 x 5"
+# [1] "26 = 2 x 13"
+# [1] "27 = 3 x 3 x 3"
+# [1] "28 = 2 x 2 x 7"
+# [1] "30 = 2 x 3 x 5"
+# [1] "32 = 2 x 2 x 2 x 2 x 2"
+# [1] "33 = 3 x 11"
+# [1] "34 = 2 x 17"
+# [1] "35 = 5 x 7"
+# [1] "38 = 2 x 19"
+# [1] "39 = 3 x 13"
+# [1] "42 = 2 x 3 x 7"
+# [1] "44 = 2 x 2 x 11"
+# [1] "45 = 3 x 3 x 5"
+# [1] "46 = 2 x 23"
+# [1] "48 = 2 x 2 x 2 x 2 x 3"
+# [1] "49 = 7 x 7"
+# [1] "50 = 2 x 5 x 5"
\ No newline at end of file
diff --git a/challenge-041/wanderdoc/R/ch-02.R b/challenge-041/wanderdoc/R/ch-02.R
new file mode 100644
index 0000000000..397aa8cb93
--- /dev/null
+++ b/challenge-041/wanderdoc/R/ch-02.R
@@ -0,0 +1,29 @@
+fib <- function(n) 
+{
+  x <- 0; y <- 1;
+
+  m <- 0;
+  while (m < n)
+  {
+    temp <-x;
+    x <- y;
+    y <- temp + y;
+    m = m + 1;
+  }
+
+  x
+}
+
+
+leonardo <- function(x)
+{
+  leo_num <- 2 * fib(x + 1) - 1
+  leo_num
+}
+
+
+sapply(1:20, leonardo)
+
+# Prints:
+# [1]     1     3     5     9    15    25    41    67   109   177   287   465   753  1219  1973
+# [16]  3193  5167  8361 13529 21891