From 0314bccaddbca7ea9935f55461a2d7bbc8bca2d6 Mon Sep 17 00:00:00 2001
From: Bruno Freitas Tissei <bft15@inf.ufpr.br>
Date: Thu, 28 Nov 2019 13:37:24 -0300
Subject: [PATCH] Improve Aho Corasick
Signed-off-by: Bruno Freitas Tissei <bft15@inf.ufpr.br>
---
algorithms/string/aho_corasick.cpp | 39 ++++++++++-------
contests/Cadernaveis/URI1141.cpp | 62 ++++++++++++++++-----------
contests/Cadernaveis/UVA10679_aho.cpp | 36 +++++++++-------
3 files changed, 81 insertions(+), 56 deletions(-)
diff --git a/algorithms/string/aho_corasick.cpp b/algorithms/string/aho_corasick.cpp
index 23f0302..f5c29f2 100644
--- a/algorithms/string/aho_corasick.cpp
+++ b/algorithms/string/aho_corasick.cpp
@@ -13,11 +13,11 @@
// *: Use only if "match_all" is necessary
struct AhoCorasick {
struct Node {
- //*: vector<int> words;
+ vector<int> words;
map<char,int> next;
- int idx, fail, cnt, hei;
+ int fail, cnt, hei, occ;
- Node() : idx(-1), fail(0), cnt(0), hei(0) {}
+ Node() : fail(0), cnt(0), hei(0), occ(-1) {}
int has(char i) { return next.count(i); }
int &operator[](char i) { return next[i]; }
};
@@ -36,7 +36,7 @@ struct AhoCorasick {
for (int i = 0; i < s.size(); n = trie[n][s[i]], ++i)
if (!trie[n].has(s[i])) {
trie[n][s[i]] = trie.size();
- //*: trie[n].hei = i + 1;
+ trie[n].hei = i + 1;
trie.pb(Node());
}
return n;
@@ -45,10 +45,8 @@ struct AhoCorasick {
void build(const vector<string> &v) {
for (int i = 0; i < v.size(); ++i) {
int n = insert(v[i]);
- trie[n].idx = i;
- //*: trie[n].words.pb(i);
+ trie[n].words.pb(i);
}
- preprocess();
}
inline int suffix(int v, char c) {
@@ -62,10 +60,14 @@ struct AhoCorasick {
for (int i = 0; i != Q.size(); ++i) {
int u = Q[i];
for (auto j : trie[u].next) {
- trie[j.se].fail = u ? suffix(trie[u].fail, j.fi) : trie[u].fail;
-
- //*: trie[j.se].words.insert(trie[j.se].words.end(),
- // all(trie[trie[j.se].fail].words));
+ int &v = trie[j.se].fail;
+ if (u) {
+ v = suffix(trie[u].fail, j.fi);
+ trie[j.se].occ = trie[v].words.size() ? v : trie[v].occ;
+ } else {
+ v = trie[u].fail;
+ trie[j.se].occ = -1;
+ }
Q.pb(j.se);
}
}
@@ -80,14 +82,13 @@ struct AhoCorasick {
u = suffix(u, i);
trie[u].cnt++;
}
-
for (int i = top.size() - 1; i >= 0; --i)
trie[trie[top[i]].fail].cnt += trie[top[i]].cnt;
vector<int> ans;
- for (auto i : trie)
- if (i.idx != -1 && i.cnt)
- ans.pb(i.idx);
+ for (auto &i : trie)
+ if (i.cnt && i.words.size())
+ for (auto j : i.words) ans.pb(j);
sort(all(ans));
return ans;
@@ -103,7 +104,15 @@ struct AhoCorasick {
u = suffix(u, p[i]);
for (auto j : trie[u].words)
ans.pb({j, i - trie[u].hei + 1});
+
+ int x = u;
+ while (trie[x].occ != -1) {
+ x = trie[x].occ;
+ for (auto j : trie[x].words)
+ ans.pb({j, i - trie[x].hei + 1});
+ }
}
+ sort(all(ans));
return ans;
}
};
diff --git a/contests/Cadernaveis/URI1141.cpp b/contests/Cadernaveis/URI1141.cpp
index 36bf967..395917e 100644
--- a/contests/Cadernaveis/URI1141.cpp
+++ b/contests/Cadernaveis/URI1141.cpp
@@ -23,11 +23,11 @@ using ii = pair<int,int>;
struct AhoCorasick {
struct Node {
- int fail;
+ int fail, occ;
vector<int> words;
map<char,int> next;
- Node() : fail(0) {}
+ Node() : fail(0), occ(-1) {}
int has(char i) { return next.count(i); }
int &operator[](char i) { return next[i]; }
};
@@ -68,8 +68,14 @@ struct AhoCorasick {
for (int i = 0; i != Q.size(); ++i) {
int u = Q[i];
for (auto j : trie[u].next) {
- trie[j.se].fail = u ? suffix(trie[u].fail, j.fi) : trie[u].fail;
- trie[j.se].words.insert(trie[j.se].words.end(), all(trie[trie[j.se].fail].words));
+ int &v = trie[j.se].fail;
+ if (u) {
+ v = suffix(trie[u].fail, j.fi);
+ trie[j.se].occ = trie[v].words.size() ? v : trie[v].occ;
+ } else {
+ v = trie[u].fail;
+ trie[j.se].occ = -1;
+ }
Q.pb(j.se);
}
}
@@ -80,22 +86,6 @@ int n;
int dp[10101];
vector<string> v;
-int solve(int i, AhoCorasick &aho) {
- if (i == n) return 0;
- if (dp[i] != -1) return dp[i];
-
- int u = 0;
- int grt = 0;
- for (auto j : v[i]) {
- u = aho.suffix(u, j);
- for (auto k : aho.trie[u].words)
- if (v[k].size() < v[i].size())
- grt = max(grt, solve(k, aho) + 1);
- }
-
- return dp[i] = grt;
-}
-
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
@@ -103,14 +93,34 @@ int main() {
while (cin >> n && n) {
v.clear();
v.resize(n);
- for (auto &i : v) cin >> i;
+ for (auto &i : v)
+ cin >> i;
+
+ sort(all(v), [](const string &a, const string &b) {
+ return a.size() > b.size();
+ });
+
AhoCorasick aho(v);
+ for (int i = n - 1; i >= 0; --i) {
+ int grt = 0, u = 0;
+ for (auto j : v[i]) {
+ u = aho.suffix(u, j);
+ for (auto k : aho.trie[u].words)
+ if (k != i)
+ grt = max(grt, dp[k] + 1);
+
+ int x = u;
+ while (aho.trie[x].occ != -1) {
+ x = aho.trie[x].occ;
+ for (auto k : aho.trie[x].words)
+ if (k != i)
+ grt = max(grt, dp[k] + 1);
+ }
+ }
+ dp[i] = grt;
+ }
- mset(dp, -1);
- int ans = 0;
- for (int i = 0; i < n; ++i)
- ans = max(ans, solve(i, aho) + 1);
- cout << ans << ende;
+ cout << (*max_element(dp, dp + n) + 1) << ende;
}
return 0;
diff --git a/contests/Cadernaveis/UVA10679_aho.cpp b/contests/Cadernaveis/UVA10679_aho.cpp
index e5e69c5..1576039 100644
--- a/contests/Cadernaveis/UVA10679_aho.cpp
+++ b/contests/Cadernaveis/UVA10679_aho.cpp
@@ -1,3 +1,5 @@
+/// I Love Strings! (Aho-Corasick)
+
#include <bits/stdc++.h>
#define MAX 1010101
@@ -22,10 +24,11 @@ using ii = pair<int,int>;
struct AhoCorasick {
struct Node {
+ int fail, occ, cnt;
+ vector<int> words;
map<char,int> next;
- int idx, fail, cnt, hei;
- Node() : idx(-1), fail(0), cnt(0), hei(0) {}
+ Node() : fail(0), occ(-1), cnt(0) {}
int has(char i) { return next.count(i); }
int &operator[](char i) { return next[i]; }
};
@@ -52,9 +55,8 @@ struct AhoCorasick {
void build(const vector<string> &v) {
for (int i = 0; i < v.size(); ++i) {
int n = insert(v[i]);
- trie[n].idx = i;
+ trie[n].words.pb(i);
}
- preprocess();
}
inline int suffix(int v, char c) {
@@ -68,7 +70,14 @@ struct AhoCorasick {
for (int i = 0; i != Q.size(); ++i) {
int u = Q[i];
for (auto j : trie[u].next) {
- trie[j.se].fail = u ? suffix(trie[u].fail, j.fi) : trie[u].fail;
+ int &v = trie[j.se].fail;
+ if (u) {
+ v = suffix(trie[u].fail, j.fi);
+ trie[j.se].occ = trie[v].words.size() ? v : trie[v].occ;
+ } else {
+ v = trie[u].fail;
+ trie[j.se].occ = -1;
+ }
Q.pb(j.se);
}
}
@@ -77,7 +86,8 @@ struct AhoCorasick {
vector<int> match(const string &p) {
int u = 0;
- for (auto i : p) {
+ vector<int> ans;
+ for (auto &i : p) {
u = suffix(u, i);
trie[u].cnt++;
}
@@ -85,12 +95,12 @@ struct AhoCorasick {
for (int i = top.size() - 1; i >= 0; --i)
trie[trie[top[i]].fail].cnt += trie[top[i]].cnt;
- vector<int> ans;
for (auto i : trie)
- if (i.idx != -1 && i.cnt)
- ans.pb(i.idx);
+ if (i.cnt && i.words.size())
+ for (auto j : i.words) ans.pb(j);
sort(all(ans));
+ ans.erase(unique(all(ans)), ans.end());
return ans;
}
};
@@ -109,16 +119,12 @@ int main() {
AhoCorasick aho(v);
vector<int> ans = aho.match(s);
- map<string,int> M;
for (int i = 0, j = 0; i < n; ++i) {
if (j < ans.size() && ans[j] == i) {
- M[v[j]] = 1; ++j;
+ cout << 'y' << ende; ++j;
} else
- if (!M[v[j]]) M[v[j]] = 0;
+ cout << 'n' << ende;
}
-
- for (int i = 0; i < n; ++i)
- cout << (M[v[i]] ? 'y' : 'n') << ende;
}
return 0;
--
GitLab