add rle

technology/files/RLE.md

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+---
+obj: concept
+wiki: https://en.wikipedia.org/wiki/Run-length_encoding
+rev: 2024-05-31
+---
+
+# Run-Length Encoding (RLE)
+Run-Length Encoding (RLE) is a simple and effective form of data compression where sequences of the same data value (runs) are stored as a single data value and a count. This technique is most efficient when data contains many such runs, making it particularly effective for repetitive data.
+
+The basic idea of RLE is to reduce the size of repetitive data by replacing sequences of identical elements with a pair that represents the element and the count of its occurrences. The steps involved in RLE are:
+
+1. **Identify Runs**: Scan the input data to identify consecutive elements that are the same.
+2. **Encode Runs**: Replace each run with a pair of values: the repeated element and the length of the run.
+
+## Example
+Consider the input string:
+
+```
+AAAABBBCCDAA
+```
+
+The RLE encoding process would work as follows:
+
+1. Identify runs: `AAAA`, `BBB`, `CC`, `D`, `AA`
+2. Encode runs: `4A`, `3B`, `2C`, `1D`, `2A`
+
+So, the encoded string would be:
+
+```
+4A3B2C1D2A
+```
+
+## Advantages and Disadvantages
+### Advantages
+- **Simplicity**: RLE is straightforward to implement.
+- **Efficiency for Repetitive Data**: RLE can significantly reduce the size of data with many runs of the same value.
+
+### Disadvantages
+- **Inefficiency for Non-Repetitive Data**: If the data does not contain many runs, RLE may not compress the data effectively asd could even increase the data size.
+- **Fixed Run Length**: The efficiency of RLE depends on the length of runs. For data without significant repetition, other compression methods might be more effective.