gno.land/p/moul/x/daily/kmp/v0⧉

# `gno.land/p/moul/x/daily/kmp/v0`

**Knuth–Morris–Pratt substring search** — `Index`, `Contains`, `FindAll`,
`Count`, `Table`, `MaxPattern`.

```go
import "gno.land/p/moul/x/daily/kmp/v0"

kmp.Index("mississippi", "issi")   // 1
kmp.FindAll("mississippi", "issi") // [1 4] — overlapping
kmp.Count("aaaa", "aa")            // 3
kmp.Table("ababaa")                // [0 0 1 2 3 1]
```

The naive scan re-compares characters it already matched, so `"aaaaaaab"` inside
`"aaaaaaaaaaaaaaab"` costs O(n·m). KMP precomputes a failure table and slides the
pattern without ever moving the text cursor backwards: **O(n+m), with no bad
case**. On chain that matters — a pathological input is an attack, not bad luck.

Two things worth knowing, each with a test:

- **`FindAll` reports overlapping matches.** `FindAll("aaaa", "aa")` is
  `[0 1 2]`, not `[0 2]` — the honest reading of "every occurrence". A caller
  wanting disjoint matches can filter; one wanting overlap could not recover it.
- **Offsets are BYTE offsets**, not runes. gno strings are UTF-8, so `Index("éx",
  "x")` is `2`. That matches `strings.Index`, and it is the right unit for
  slicing.

`Index` is pinned against `strings.Index` across a spread of inputs: same
contract, different algorithm.

**Live demo:** [`r/moul/x/daily/kmpdemo`](https://github.com/moul/gno-contracts/tree/main/r/moul/x/daily/kmpdemo/v0)
· render it at [`/r/moul/x/daily/kmpdemo/v0`](https://gno.land/r/moul/x/daily/kmpdemo/v0).

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Part of **[moul/gno-contracts](https://github.com/moul/gno-contracts)** — moul's versioned gno.land contracts. See the repository for the full catalog, build/test tooling, and usage.

> 🧪 **Highly experimental — potentially vibe-coded.** Not audited; may break, change, or be removed at any time. Do not use with anything of value. Full disclaimer: [DISCLAIMER](https://github.com/moul/gno-contracts/blob/main/DISCLAIMER.md).

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