Diff Algorithms Explained: Myers, Patience, and Histogram Diffs
Understand the algorithms behind diff tools: Myers shortest edit script, Patience diff for readable output, and Histogram diff used in Git.
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Tags: developer-tools, diff, algorithms
Diff Algorithms Explained: Myers, Patience, and Histogram Diffs Every time you run or open a pull request, a diff algorithm is deciding which lines to pair between the old and new version of a file. The algorithm choice affects whether the output is readable or confusing — whether moved functions look like total rewrites or clean relocations. Three algorithms dominate modern tooling: Myers (1986), Patience, and Histogram. Here's how each works and when to reach for each one. Myers Algorithm (1986) Myers is the algorithm in GNU , and it was Git's default until version 2.35. The original paper is "An O(ND) Difference Algorithm and Its Variations" by Eugene Myers. How it works Myers models the problem as a graph search. Imagine a grid where the X-axis represents positions in the old file and…
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