[關鍵字]: lengths of runs of equal values in a vector
[出處]:
https://stat.ethz.ch/R-manual/R-devel/library/base/html/rle.html
[重點摘要]:
以前沒看過的指令，感覺很實用
並且改寫一個Rcpp的版本：http://pastebin.com/0NbM1qbB

thanks for sharing the good example~~