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SA-IS Algorithm for linear time/space suffix array construction
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| namespace SA { | |
| int sa[N], rk[N], ht[N], s[N<<1], t[N<<1], p[N], cnt[N], cur[N]; | |
| #define pushS(x) sa[cur[s[x]]--] = x | |
| #define pushL(x) sa[cur[s[x]]++] = x | |
| #define inducedSort(v) fill_n(sa, n, -1); fill_n(cnt, m, 0); \ | |
| for (int i = 0; i < n; i++) cnt[s[i]]++; \ | |
| for (int i = 1; i < m; i++) cnt[i] += cnt[i-1]; \ | |
| for (int i = 0; i < m; i++) cur[i] = cnt[i]-1; \ | |
| for (int i = n1-1; ~i; i--) pushS(v[i]); \ | |
| for (int i = 1; i < m; i++) cur[i] = cnt[i-1]; \ | |
| for (int i = 0; i < n; i++) if (sa[i] > 0 && t[sa[i]-1]) pushL(sa[i]-1); \ | |
| for (int i = 0; i < m; i++) cur[i] = cnt[i]-1; \ | |
| for (int i = n-1; ~i; i--) if (sa[i] > 0 && !t[sa[i]-1]) pushS(sa[i]-1) | |
| void sais(int n, int m, int *s, int *t, int *p) { | |
| int n1 = t[n-1] = 0, ch = rk[0] = -1, *s1 = s+n; | |
| for (int i = n-2; ~i; i--) t[i] = s[i] == s[i+1] ? t[i+1] : s[i] > s[i+1]; | |
| for (int i = 1; i < n; i++) rk[i] = t[i-1] && !t[i] ? (p[n1] = i, n1++) : -1; | |
| inducedSort(p); | |
| for (int i = 0, x, y; i < n; i++) if (~(x = rk[sa[i]])) { | |
| if (ch < 1 || p[x+1] - p[x] != p[y+1] - p[y]) ch++; | |
| else for (int j = p[x], k = p[y]; j <= p[x+1]; j++, k++) | |
| if ((s[j]<<1|t[j]) != (s[k]<<1|t[k])) {ch++; break;} | |
| s1[y = x] = ch; | |
| } | |
| if (ch+1 < n1) sais(n1, ch+1, s1, t+n, p+n1); | |
| else for (int i = 0; i < n1; i++) sa[s1[i]] = i; | |
| for (int i = 0; i < n1; i++) s1[i] = p[sa[i]]; | |
| inducedSort(s1); | |
| } | |
| template<typename T> | |
| int mapCharToInt(int n, const T *str) { | |
| int m = *max_element(str, str+n); | |
| fill_n(rk, m+1, 0); | |
| for (int i = 0; i < n; i++) rk[str[i]] = 1; | |
| for (int i = 0; i < m; i++) rk[i+1] += rk[i]; | |
| for (int i = 0; i < n; i++) s[i] = rk[str[i]] - 1; | |
| return rk[m]; | |
| } | |
| // Ensure that str[n] is the unique lexicographically smallest character in str. | |
| template<typename T> | |
| void suffixArray(int n, const T *str) { | |
| int m = mapCharToInt(++n, str); | |
| sais(n, m, s, t, p); | |
| for (int i = 0; i < n; i++) rk[sa[i]] = i; | |
| for (int i = 0, h = ht[0] = 0; i < n-1; i++) { | |
| int j = sa[rk[i]-1]; | |
| while (i+h < n && j+h < n && s[i+h] == s[j+h]) h++; | |
| if (ht[rk[i]] = h) h--; | |
| } | |
| } | |
| }; |
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