From facbf6ea3aa58bb3ba68c79e0947451a88fca7a7 Mon Sep 17 00:00:00 2001 From: Anthony Green Date: Thu, 8 May 2014 07:20:11 +0100 Subject: [PATCH] Add circular buffer exercise --- circular-buffer.md | 22 ++++++++++++++++++++++ circular-buffer.yml | 4 ++++ 2 files changed, 26 insertions(+) create mode 100644 circular-buffer.md create mode 100644 circular-buffer.yml diff --git a/circular-buffer.md b/circular-buffer.md new file mode 100644 index 0000000000..dcfa832d1d --- /dev/null +++ b/circular-buffer.md @@ -0,0 +1,22 @@ +A circular buffer, cyclic buffer or ring buffer is a data structure that uses a single, fixed-size buffer as if it were connected end-to-end. + +A circular buffer first starts empty and of some predefined length. For example, this is a 7-element buffer: +[ ][ ][ ][ ][ ][ ][ ] + +Assume that a 1 is written into the middle of the buffer (exact starting location does not matter in a circular buffer): +[ ][ ][ ][1][ ][ ][ ] + +Then assume that two more elements are added — 2 & 3 — which get appended after the 1: +[ ][ ][ ][1][2][3][ ] + +If two elements are then removed from the buffer, the oldest values inside the buffer are removed. The two elements removed, in this case, are 1 & 2, leaving the buffer with just a 3: +[ ][ ][ ][ ][ ][3][ ] + +If the buffer has 7 elements then it is completely full: +[6][7][8][9][3][4][5] + +A consequence of the circular buffer is that when it is full and a subsequent write is performed, then it starts overwriting the oldest data. In this case, two more elements — A & B — are added and they overwrite the 3 & 4: +[6][7][8][9][A][B][5] + +Finally, if two elements are now removed then what would be returned is not 3 & 4 but 5 & 6 because A & B overwrote the 3 & the 4 yielding the buffer with: +[ ][7][8][9][A][B][ ] \ No newline at end of file diff --git a/circular-buffer.yml b/circular-buffer.yml new file mode 100644 index 0000000000..0b5837f98b --- /dev/null +++ b/circular-buffer.yml @@ -0,0 +1,4 @@ +--- +blurb: "A data structure that uses a single, fixed-size buffer as if it were connected end-to-end." +source: "Wikipedia" +source_url: "http://en.wikipedia.org/wiki/Circular_buffer"