1 files changed, 50 insertions, 53 deletions

diff --git a/string/ahoCorasick.cpp b/string/ahoCorasick.cpp
index d221fcb..530490e 100644
--- a/string/ahoCorasick.cpp
+++ b/string/ahoCorasick.cpp
@@ -1,57 +1,54 @@
-// Laufzeit: O(n + m + z), n = #Text, m = Summe #Pattern, z = #Matches
-// Findet mehrere Patterns gleichzeitig in einem String.
-// 1) Wurzel erstellen: aho.push_back(vertex());
-// 2) Mit addString(0, pattern, idx); Patterns hinzufügen.
-// 3) finishAutomaton(0) aufrufen.
-// 4) Mit state = go(state, c) in nächsten Zustand wechseln.
-//    DANACH: Wenn patterns-Vektor nicht leer ist: Hier enden alle
-//    enthaltenen Patterns.
-// ACHTUNG: Die Zahlenwerte der auftretenden Buchstaben müssen
-// zusammenhängend sein und bei 0 beginnen!
-struct vertex {
-  int next[ALPHABET_SIZE], failure;
-  int character; 
-  vector<int> patterns; // Indizes der Patterns, die hier enden.
-  vertex() { for (int i = 0; i < ALPHABET_SIZE; i++) next[i] = -1; }
-};
-vector<vertex> aho;
+constexpr ll ALPHABET_SIZE = 26;
+constexpr char OFFSET = 26;
+struct AhoCorasick {
+	struct vert {
+		int suffix, exit, character, parent;
+		vector<int> nxt, patterns;
+		vert(int c, int p) : suffix(-1), exit(-1), 
+				 character(c), nxt(ALPHABET_SIZE, -1), parent(p) {}
+	};
+	vector<vert> aho;
 
-void addString(int v, vector<int> &pattern, int patternIdx) {
-  for (int i = 0; i < (int)pattern.size(); i++) {
-    if (aho[v].next[pattern[i]] == -1) {
-      aho[v].next[pattern[i]] = aho.size();
-      aho.push_back(vertex());
-      aho.back().character = pattern[i];
-    }
-    v = aho[v].next[pattern[i]];
-  }
-  aho[v].patterns.push_back(patternIdx);
-}
+	AhoCorasick() {aho.push_back(vert(-1, 0));}
 
-void finishAutomaton(int v) {
-  for (int i = 0; i < ALPHABET_SIZE; i++)
-    if (aho[v].next[i] == -1) aho[v].next[i] = v;
+	// Call once for each pattern.
+	void addString(string &s, int patternIdx) {
+		int v = 0;
+		for (char c : s) {
+			int idx = c - OFFSET;
+			if (aho[v].nxt[idx] == -1) {
+				aho[v].nxt[idx] = sz(aho);
+				aho.emplace_back(idx, v);
+			}
+			v = aho[v].nxt[idx];
+		}
+		aho[v].patterns.push_back(patternIdx);
+	}
 
-  queue<int> q;
-  for (int i = 0; i < ALPHABET_SIZE; i++) {
-    if (aho[v].next[i] != v) {
-      aho[aho[v].next[i]].failure = v;
-      q.push(aho[v].next[i]);
-  }}
-  while (!q.empty()) {
-    int r = q.front(); q.pop();
-    for (int i = 0; i < ALPHABET_SIZE; i++) {
-      if (aho[r].next[i] != -1) {
-        q.push(aho[r].next[i]);
-        int f = aho[r].failure;
-        while (aho[f].next[i] == -1) f = aho[f].failure;
-        aho[aho[r].next[i]].failure = aho[f].next[i];
-        for (int j = 0; j < (int)aho[aho[f].next[i]].patterns.size(); j++) {
-          aho[aho[r].next[i]].patterns.push_back(
-              aho[aho[f].next[i]].patterns[j]);
-}}}}}
+	int getSuffix(int v) {
+		if (aho[v].suffix == -1) {
+			if (v == 0 || aho[v].parent == 0) aho[v].suffix = 0;
+			else aho[v].suffix = go(getSuffix(aho[v].parent), 
+															aho[v].character);
+		}
+		return aho[v].suffix;
+	}
 
-int go(int v, int c) {
-  if (aho[v].next[c] != -1) return aho[v].next[c];
-  else return go(aho[v].failure, c);
-}
+	int getExit(int v) {
+		if (aho[v].exit == -1) {
+			int suffix = getSuffix(v);
+			if (v == 0) aho[v].exit = 0;
+			else {
+				if (aho[suffix].patterns.empty()) {
+					aho[v].exit = getExit(suffix);
+				} else {
+					aho[v].exit = suffix;
+		}}}
+		return aho[v].exit;
+	}
+
+	int go(int v, int idx) { // Root is v=0.
+		if (aho[v].nxt[idx] != -1) return aho[v].nxt[idx];
+		else return v == 0 ? 0 : go(getSuffix(v), idx);
+	}
+};
\ No newline at end of file