Data commit

Task/ABC-problem/R/abc-problem-1.r

@@ -0,0 +1,43 @@
+blocks <- rbind(c("B","O"),
+ c("X","K"),
+ c("D","Q"),
+ c("C","P"),
+ c("N","A"),
+ c("G","T"),
+ c("R","E"),
+ c("T","G"),
+ c("Q","D"),
+ c("F","S"),
+ c("J","W"),
+ c("H","U"),
+ c("V","I"),
+ c("A","N"),
+ c("O","B"),
+ c("E","R"),
+ c("F","S"),
+ c("L","Y"),
+ c("P","C"),
+ c("Z","M"))
+
+canMake <- function(x) {
+  x <- toupper(x)
+  used <- rep(FALSE, dim(blocks)[1L])
+  charList <- strsplit(x, character(0))
+  tryChars <- function(chars, pos, used, inUse=NA) {
+    if (pos > length(chars)) {
+      TRUE
+    } else {
+      used[inUse] <- TRUE
+      possible <- which(blocks == chars[pos] & !used, arr.ind=TRUE)[, 1L]
+      any(vapply(possible, function(possBlock) tryChars(chars, pos + 1, used, possBlock), logical(1)))
+    }
+  }
+  setNames(vapply(charList, tryChars, logical(1), 1L, used), x)
+}
+canMake(c("A",
+           "BARK",
+           "BOOK",
+           "TREAT",
+           "COMMON",
+           "SQUAD",
+           "CONFUSE"))

Task/ABC-problem/R/abc-problem-2.r

@@ -0,0 +1,21 @@
+canMakeNoRecursion <- function(x) {
+  x <- toupper(x)
+  charList <- strsplit(x, character(0))
+  getCombos <- function(chars) {
+    charBlocks <-  data.matrix(expand.grid(lapply(chars, function(char) which(blocks == char, arr.ind=TRUE)[, 1L])))
+    charBlocks <- charBlocks[!apply(charBlocks, 1, function(row) any(duplicated(row))), , drop=FALSE]
+    if (dim(charBlocks)[1L] > 0L) {
+      t(apply(charBlocks, 1, function(row) apply(blocks[row, , drop=FALSE], 1, paste, collapse="")))
+    } else {
+      character(0)
+    }
+  }
+  setNames(lapply(charList, getCombos), x)
+}
+canMakeNoRecursion(c("A",
+           "BARK",
+           "BOOK",
+           "TREAT",
+           "COMMON",
+           "SQUAD",
+           "CONFUSE"))