Balanced brackets: Difference between revisions

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@@ Line 1,359: / Line 1,359: @@
 =={{header|R}}==
-<lang r>rand.parens <- function(n) paste(permute(c(rep('[',n),rep(']',n))),collapse="")
+<lang r>balanced <- function(str){
-balanced <- function(str){
   str <- strsplit(str, "")[[1]]
   str <- ifelse(str=='[', 1, -1)
   all(cumsum(str) >= 0) && sum(str) == 0
+}</lang>
-}
-#Alternately, using perl 5.10-compatible regexps
+Alternately, using perl 5.10-compatible regexps,
-balanced <- function(str) {
+<lang r>balanced <- function(str) {
   regexpr('^(\\[(?1)*\\])*$', str, perl=TRUE) > -1
+}</lang>
-}
+To generate some some examples:
+<lang R>rand.parens <- function(n) paste(permute(c(rep('[',n),rep(']',n))),collapse="")
-#generate some examples
 as.data.frame(within(list(), {
   parens <- replicate(10, rand.parens(sample.int(10,size=1)))
   balanced <- sapply(parens, balanced)
-}))
+}))</lang>
-</lang>
+Output:
-Sample output:
 <lang r>   balanced             parens
 FALSE               ][][