day03

Author: plannapus

2024/day03.R

@@ -0,0 +1,17 @@
+r <- paste0(readLines(read.input(3)),collapse="")
+s <- strsplit(gsub("mul\\(|\\)","",regmatches(r,gregexpr("mul\\([0-9]+,[0-9]+\\)",r))[[1]]),",")
+m <- apply(do.call(rbind,s),2,as.integer)
+sum(apply(m,1,prod))
+#173419328
+
+inst <- regmatches(r,gregexpr("(mul\\([0-9]+,[0-9]+\\))|(do\\(\\))|(don\\'t\\(\\))",r))[[1]]
+
+do <- TRUE
+a <- 0
+for(i in seq_along(inst)){
+  if(inst[i]=="do()") do <- TRUE
+  if(inst[i]=="don't()") do <- FALSE
+  if(grepl("mul",inst[i])&do) a <- a + prod(as.integer(strsplit(gsub("(mul\\()|\\)","",inst[i]),",")[[1]]))
+}
+a
+#90669332

2024/parse.group.R

@@ -0,0 +1,10 @@
+parse.group <- function(regex,input) { #old faithful (from regexpr help file)
+  result <- regexpr(regex, input, perl=TRUE)
+  m <- do.call(rbind, lapply(seq_along(input), function(i) {
+    if(result[i] == -1) return("")
+    st <- attr(result, "capture.start")[i, ]
+    substring(input[i], st, st + attr(result, "capture.length")[i, ] - 1)
+  }))
+  colnames(m) <- attr(result, "capture.names")
+  as.data.frame(m)
+}