From 78bac3ae8a361a2236cad60214c918ef476bc411 Mon Sep 17 00:00:00 2001
From: Zengtudor <Zengtudor@outlook.com>
Date: Thu, 21 Aug 2025 10:08:42 +0800
Subject: [PATCH] update

---
 src/8/20/P2312.cpp | 18 ++++++------
 src/8/21/kmp.cpp   | 72 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+), 9 deletions(-)
 create mode 100644 src/8/21/kmp.cpp

diff --git a/src/8/20/P2312.cpp b/src/8/20/P2312.cpp
index aa14d40..5273250 100644
--- a/src/8/20/P2312.cpp
+++ b/src/8/20/P2312.cpp
@@ -6,11 +6,11 @@
 using i128 = __int128_t;
 using ll = int64_t;
 
-ll n, m;
-const std::vector<ll> mods = {(ll)1e9+7};
-std::vector<std::vector<ll>> a;
+static ll n, m;
+static const ll mod = 1e9+7;
+static std::vector<std::vector<ll>> a;
 
-ll strp(const std::string &s, ll p) {
+static inline constexpr ll strp(const std::string &s, ll p) {
     ll num = 0;
     int idx = 0;
     ll nag = 1;
@@ -34,12 +34,12 @@ int main() {
     std::cin.tie(NULL);
 
     std::cin >> n >> m;
-    a.resize(n + 1, std::vector<ll>(mods.size()));
+    a.resize(n + 1, std::vector<ll>(1));
     for (int i = 0; i <= n; ++i) {
         std::string tmpstr;
         std::cin >> tmpstr;
-        for (size_t k = 0; k < mods.size(); ++k) {
-            a[i][k] = strp(tmpstr, mods[k]);
+        for (size_t k = 0; k < 1; ++k) {
+            a[i][k] = strp(tmpstr,mod);
         }
     }
 
@@ -48,9 +48,9 @@ int main() {
 
     for (ll i = 1; i <= m; ++i) {
         bool isok = true;
-        for (size_t k = 0; k < mods.size(); ++k) {
+        for (size_t k = 0; k < 1; ++k) {
 
-            const ll p = mods[k];
+            const ll p = mod;
             const auto &cur = a;
 
             ll curx = 1;
diff --git a/src/8/21/kmp.cpp b/src/8/21/kmp.cpp
new file mode 100644
index 0000000..863fd7a
--- /dev/null
+++ b/src/8/21/kmp.cpp
@@ -0,0 +1,72 @@
+#include <iostream>
+#include <string>
+#include <vector>
+
+std::vector<int> compute_next(const std::string &p) {
+    int m = p.length();
+    std::vector<int> next(m, 0);
+
+    for (int i = 1, j = 0; i < m; ++i) {
+
+        while (j > 0 && p[i] != p[j]) {
+            j = next[j - 1];
+        }
+
+        if (p[i] == p[j]) {
+            j++;
+        }
+
+        next[i] = j;
+    }
+
+    return next;
+}
+
+std::vector<int> kmp_search(const std::string &text, const std::string &p) {
+    int n = text.length();
+    int m = p.length();
+
+    if (m == 0)
+        return {};
+    if (n < m)
+        return {};
+
+    std::vector<int> next = compute_next(p);
+    std::vector<int> res;
+
+    for (int i = 0, j = 0; i < n; ++i) {
+        while (j > 0 && text[i] != p[j]) {
+            j = next[j - 1];
+        }
+        if (text[i] == p[j]) {
+            j++;
+        }
+        if (j == m) {
+            res.push_back(i - m + 1);
+            j = next[j - 1];
+        }
+    }
+    return res;
+}
+
+int main() {
+    std::string text = "ABABDABACDABABCABAB";
+    std::string p = "ABABCABAB";
+
+    std::cout << "Text:    " << text << std::endl;
+    std::cout << "p: " << p << std::endl;
+
+    std::vector<int> ans1 = kmp_search(text, p);
+
+    if (ans1.empty()) {
+        std::cout << "p not found " << std::endl;
+    } else {
+        std::cout << "p found at ";
+        for (size_t i = 0; i < ans1.size(); ++i) {
+            std::cout << ans1[i] << (i == ans1.size() - 1 ? "" : ", ");
+        }
+        std::cout << std::endl;
+    }
+
+    return 0;
+}