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Update sa.cc

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Ariel 2024-01-21 10:06:30 +08:00 committed by GitHub
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commit cf752da653
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1 changed files with 30 additions and 46 deletions
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string/sa.cc
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@ -1,59 +1,43 @@
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <iostream>
#include "../include.hh"
using namespace std;
const int N = 1000010;
constexpr int N = 1e6 + 10;
char s[N];
// key1[i] = rk[id[i]]（作为基数排序的第一关键字数组）
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];
}
int main() {
int i, m = 127, p, 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;
scanf("%s", s + 1);
n = strlen(s + 1);
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;
// calc sa[]
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;
memset(cnt, 0, sizeof(cnt));
for (i = 1; i <= n; ++i) ++cnt[key1[i] = rk[id[i]]];
for (w = 1;; w <<= 1, m = p) { // m=p 就是优化计数排序值域
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]]];
// 注意这里px[i] != i，因为rk没有更新，是上一轮的排名数组
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;
}
}
// 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;
}
for (i = 1; i <= n; ++i) printf("%d ", sa[i]);
return 0;
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;
}
}
}
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];
}