feat: Add R program to count unique letters in a string

sorting_algorithms/cocktail_sort.r

@@ -1,56 +1,47 @@
-cocktailSort <- function(arr) {
+# Cocktail Sort in R
+cocktail.sort <- function(arr) {
   n <- length(arr)
   swapped <- TRUE
-  beg <- 1
+  start <- 1
   end <- n - 1
 
   while (swapped) {
     swapped <- FALSE
 
-    # Forward pass (left to right)
-    for (i in seq(beg, end)) {
+    # Forward pass
+    for (i in seq(start, end)) {
       if (arr[i] > arr[i + 1]) {
-        # Swap arr[i] and arr[i + 1]
         temp <- arr[i]
         arr[i] <- arr[i + 1]
         arr[i + 1] <- temp
         swapped <- TRUE
       }
     }
 
-    # If no swaps occurred in the forward pass, the array is sorted
-    if (!swapped) {
-      break
-    }
+    if (!swapped) break
 
     swapped <- FALSE
     end <- end - 1
 
-    # Backward pass (right to left)
-    for (i in seq(end, beg, by = -1)) {
+    # Backward pass
+    for (i in seq(end, start, by = -1)) {
       if (arr[i] > arr[i + 1]) {
-        # Swap arr[i] and arr[i + 1]
         temp <- arr[i]
         arr[i] <- arr[i + 1]
         arr[i + 1] <- temp
         swapped <- TRUE
       }
     }
 
-    beg <- beg + 1
+    start <- start + 1
   }
 
   return(arr)
 }
 
-# Example Usage
-unsorted_array <- c(38, 27, 43, 3, 9, 82, 10)
-cat("Unsorted Array: ", unsorted_array, "\n")
-
-# Call the Cocktail Sort function to sort the array
-sorted_array <- cocktailSort(unsorted_array)
-
-cat("Sorted Array: ", sorted_array, "\n")
-
-# Example: The 'unsorted_array' is sorted using Cocktail Sort
+# Example usage
+unsorted.array <- c(38, 27, 43, 3, 9, 82, 10)
+cat("Unsorted Array:", unsorted.array, "\n")
 
+sorted.array <- cocktail.sort(unsorted.array)
+cat("Sorted Array:  ", sorted.array, "\n")

string_manipulation/unique.letters.count.R

@@ -0,0 +1,20 @@
+# Ask for user input
+input.string <- readline(prompt = "Enter a string: ")
+
+# Convert to lowercase and remove non-letter characters
+clean.string <- tolower(gsub("[^a-z]", "", input.string))
+
+# Split string into individual letters
+letters.vec <- strsplit(clean.string, "")[[1]]
+
+# Get unique letters
+unique.letters <- unique(letters.vec)
+
+# Count occurrences of each unique letter
+letter.counts <- table(letters.vec)
+
+# Display results
+cat("Unique letters and their counts:\n")
+for (letter in unique.letters) {
+  cat(letter, ":", letter.counts[letter], "\n")
+}