From e77423160857cb6056ad4c13af448aaea059d0b9 Mon Sep 17 00:00:00 2001
From: subcrip <contact@subc.rip>
Date: Wed, 30 Oct 2024 18:46:54 +0800
Subject: [PATCH] Update string/sa.cc

Signed-off-by: subcrip <contact@subc.rip>
---
 string/sa.cc | 142 ++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 94 insertions(+), 48 deletions(-)

diff --git a/string/sa.cc b/string/sa.cc
index ee477b0..9b79543 100644
--- a/string/sa.cc
+++ b/string/sa.cc
@@ -1,52 +1,98 @@
-#include "../include.hh"
+struct SA {
+    int n;
+    std::vector<int> sa, rk, lc;
+    vector<vector<int>> st;
 
-constexpr int N = 1e6 + 10;
-
-char s[N];
-int n, sa[N], rk[N], oldrk[N << 1], id[N], key1[N], cnt[N], height[N];
-
-bool cmp(int x, int y, int w) {
-  return oldrk[x] == oldrk[y] && oldrk[x + w] == oldrk[y + w];
-}
-
-void calc_sa() {
-    n = strlen(s + 1);
-    int i, m = 127, p, w;
-    for (i = 1; i <= n; ++i) ++cnt[rk[i] = s[i]];
-      for (i = 1; i <= m; ++i) cnt[i] += cnt[i - 1];
-      for (i = n; i >= 1; --i) sa[cnt[rk[i]]--] = i;
-
-      for (w = 1;; w <<= 1, m = p) {
-        for (p = 0, i = n; i > n - w; --i) id[++p] = i;
-        for (i = 1; i <= n; ++i)
-          if (sa[i] > w) id[++p] = sa[i] - w;
-
-        memset(cnt, 0, sizeof(cnt));
-        for (i = 1; i <= n; ++i) ++cnt[key1[i] = rk[id[i]]];
-
-        for (i = 1; i <= m; ++i) cnt[i] += cnt[i - 1];
-        for (i = n; i >= 1; --i) sa[cnt[key1[i]]--] = id[i];
-        memcpy(oldrk + 1, rk + 1, n * sizeof(int));
-        for (p = 0, i = 1; i <= n; ++i)
-          rk[sa[i]] = cmp(sa[i], sa[i - 1], w) ? p : ++p;
-        if (p == n) {
-          break;
+    SA(std::string s) {
+        n = s.size();
+        sa.resize(n);
+        lc.resize(n - 1);
+        rk.resize(n);
+        std::iota(sa.begin(), sa.end(), 0);
+        sort_by_key(sa.begin(), sa.end(), expr(s[i], int i));
+        rk[sa[0]] = 0;
+        for (int i = 1; i < n; i++) {
+            rk[sa[i]] = rk[sa[i - 1]] + (s[sa[i]] != s[sa[i - 1]]);
         }
-      }
-}
+        int k = 1;
+        std::vector<int> tmp, cnt(n);
+        tmp.reserve(n);
+        while (rk[sa[n - 1]] < n - 1) {
+            tmp.clear();
+            for (int i = 0; i < k; i++) {
+                tmp.push_back(n - k + i);
+            }
+            for (auto i : sa) {
+                if (i >= k) {
+                    tmp.push_back(i - k);
+                }
+            }
+            std::fill(cnt.begin(), cnt.end(), 0);
+            for (int i = 0; i < n; i++) {
+                cnt[rk[i]]++;
+            }
+            for (int i = 1; i < n; i++) {
+                cnt[i] += cnt[i - 1];
+            }
+            for (int i = n - 1; i >= 0; i--) {
+                sa[--cnt[rk[tmp[i]]]] = tmp[i];
+            }
+            std::swap(rk, tmp);
+            rk[sa[0]] = 0;
+            for (int i = 1; i < n; i++) {
+                rk[sa[i]] = rk[sa[i - 1]] + (tmp[sa[i - 1]] < tmp[sa[i]] || sa[i - 1] + k == n || tmp[sa[i - 1] + k] < tmp[sa[i] + k]);
+            }
+            k *= 2;
+        }
+        for (int i = 0, j = 0; i < n; i++) {
+            if (rk[i] == 0) {
+                j = 0;
+            } else {
+                for (j -= j > 0; i + j < n && sa[rk[i] - 1] + j < n && s[i + j] == s[sa[rk[i] - 1] + j]; ) {
+                    j++;
+                }
+                lc[rk[i] - 1] = j;
+            }
+        }
+        int m = lc.size();
+        int lgm = lg2(m);
+        st = vector(lgm + 1, vector<int>(m));
+        st[0] = lc;
+        for (int j = 0; j < lgm; j++) {
+            for (int i = 0; i + (2 << j) <= m; i++) {
+                st[j + 1][i] = std::min(st[j][i], st[j][i + (1 << j)]);
+            }
+        }
+    }
 
-void calc_height() {
-  for (i = 1, k = 0; i <= n; ++i) {
-    if (rk[i] == 0) continue;
-    if (k) --k;
-    while (s[i + k] == s[sa[rk[i] - 1] + k]) ++k;
-    height[rk[i]] = k;
-  }
-}
+    int rmq(int l, int r) {
+        int k = lg2(r - l);
+        return std::min(st[k][l], st[k][r - (1 << k)]);
+    }
 
-int main() {
-    untie;
-    cin >> (s + 1);  // array s starts from index 1
-    calc_sa();
-    for (int i = 1; i <= n; ++i) cout << sa[i] << " \n"[i == n];
-}
+    __attribute__((target("lzcnt")))
+    int lcp(int i, int j) {
+        if (i == j || i == n || j == n) {
+            return std::min(n - i, n - j);
+        }
+        int a = rk[i];
+        int b = rk[j];
+        if (a > b) {
+            std::swap(a, b);
+        }
+        deb(a, b, rmq(a, b));
+        return std::min({n - i, n - j, rmq(a, b)});
+    }
+
+    int lcs(int i, int j) {
+        if (i == j || i == 0 || j == 0) {
+            return std::min(i, j);
+        }
+        int a = rk[n + n - i];
+        int b = rk[n + n - j];
+        if (a > b) {
+            std::swap(a, b);
+        }
+        return std::min({i, j, rmq(a, b)});
+    }
+};