// find the suffix array SA of s[0..n-1] in {1..K}^n
// require s[n]=s[n+1]=s[n+2]=0, n>=2
void suffixArray(int* s, int* SA, uint32_t n, uint32_t K) {
uint32_t n0=(n+2)/3, n1=(n+1)/3, n2=n/3, n02=n0+n2;
int* s12 = new int[n02 + 3]; s12[n02]= s12[n02+1]= s12[n02+2]=0;
int* SA12 = new int[n02 + 3]; SA12[n02]=SA12[n02+1]=SA12[n02+2]=0;
int* s0 = new int[n0];
int* SA0 = new int[n0];
// generate positions of mod 1 and mod 2 suffixes
// the "+(n0-n1)" adds a dummy mod 1 suffix if n%3 == 1
for (uint32_t i=0, j=0; i < n+(n0-n1); i++) if (i%3 != 0) s12[j++] = i;
// lsb radix sort the mod 1 and mod 2 triples
radixPass(s12 , SA12, s+2, n02, K);
radixPass(SA12, s12 , s+1, n02, K);
radixPass(s12 , SA12, s , n02, K);
// find lexicographic names of triples
int name = 0, c0 = -1, c1 = -1, c2 = -1;
for (uint32_t i = 0; i < n02; i++) {
if (s[SA12[i]] != c0 || s[SA12[i]+1] != c1 || s[SA12[i]+2] != c2) {
name++; c0 = s[SA12[i]]; c1 = s[SA12[i]+1]; c2 = s[SA12[i]+2];
}
if (SA12[i] % 3 == 1) { s12[SA12[i]/3] = name; } // left half
else { s12[SA12[i]/3 + n0] = name; } // right half
}
// recurse if names are not yet unique
if (name < n02) {
suffixArray(s12, SA12, n02, name);
// store unique names in s12 using the suffix array
for (uint32_t i = 0; i < n02; i++) s12[SA12[i]] = i + 1;
} else // generate the suffix array of s12 directly
for (uint32_t i = 0; i < n02; i++) SA12[s12[i] - 1] = i;
// stably sort the mod 0 suffixes from SA12 by their first character
for (uint32_t i=0, j=0; i < n02; i++) if (SA12[i] < n0) s0[j++] = 3*SA12[i];
radixPass(s0, SA0, s, n0, K);
// merge sorted SA0 suffixes and sorted SA12 suffixes
for (uint32_t p=0, t=n0-n1, k=0; k < n; k++) {
#define GetI() (SA12[t] < n0 ? SA12[t] * 3 + 1 : (SA12[t] - n0) * 3 + 2)
int i = GetI(); // pos of current offset 12 suffix
int j = SA0[p]; // pos of current offset 0 suffix
if (SA12[t] < n0 ?
leq(s[i], s12[SA12[t] + n0], s[j], s12[j/3]) :
leq(s[i],s[i+1],s12[SA12[t]-n0+1], s[j],s[j+1],s12[j/3+n0]))
{ // suffix from SA12 is smaller
SA[k] = i; t++;
if (t == n02) { // done --- only SA0 suffixes left
for (k++; p < n0; p++, k++) SA[k] = SA0[p];
}
} else {
SA[k] = j; p++;
if (p == n0) { // done --- only SA12 suffixes left
for (k++; t < n02; t++, k++) SA[k] = GetI();
}
}
}
delete [] s12; delete [] SA12; delete [] SA0; delete [] s0;
}
void suffixArray(VI &T, VI &SA, int n, int K) {
int n0 = (n + 2) / 3, n1 = (n + 1) / 3, n2 = n / 3, n02 = n0 + n2;
VI R(n02+3), SA12(n02+3), R0(n0), SA0(n0);
for (int i = 0, j = 0; i < n + (n0 - n1); i++)
if (i % 3 != 0)
R[j++] = i;
radixPass(R, SA12, T.begin() + 2, n02, K);
radixPass(SA12, R, T.begin() + 1, n02, K);
radixPass(R, SA12, T.begin(), n02, K);
int name = 0, c0 = -1, c1 = -1, c2 = -1;
for (int i = 0; i < n02; i++) {
if (T[SA12[i]] != c0 || T[SA12[i] + 1] != c1 || T[SA12[i] + 2] != c2) {
name++;
c0 = T[SA12[i]];
c1 = T[SA12[i] + 1];
c2 = T[SA12[i] + 2];
}
if (SA12[i] % 3 == 1) {
R[SA12[i] / 3] = name;
}
else {
R[SA12[i] / 3 + n0] = name;
}
}
if (name < n02) {
suffixArray(R, SA12, n02, name);
for (int i = 0; i < n02; i++)
R[SA12[i]] = i + 1;
} else
for (int i = 0; i < n02; i++)
SA12[R[i] - 1] = i;
for (int i = 0, j = 0; i < n02; i++)
if (SA12[i] < n0)
R0[j++] = 3 * SA12[i];
radixPass(R0, SA0, T.begin(), n0, K);
for (int p = 0, t = n0 - n1, k = 0; k < n; k++) {
#define GetI() (SA12[t] < n0 ? SA12[t] * 3 + 1 : (SA12[t] - n0) * 3 + 2)
int i = GetI(); // pos of current offset 12 suffix
int j = SA0[p]; // pos of current offset 0 suffix
if (SA12[t] < n0 ? // different compares for mod 1 and mod 2 suffixes
leq(T[i], R[SA12[t] + n0], T[j], R[j / 3]) :
leq(T[i], T[i + 1], R[SA12[t] - n0 + 1], T[j], T[j + 1], R[j / 3 + n0])) { // suffix from SA12 is smaller
SA[k] = i;
t++;
if (t == n02) // done --- only SA0 suffixes left
for (k++; p < n0; p++, k++)
SA[k] = SA0[p];
} else { // suffix from SA0 is smaller
SA[k] = j;
p++;
if (p == n0) // done --- only SA12 suffixes left
for (k++; t < n02; t++, k++)
SA[k] = GetI();
}
}
}
// find the suffix array SA of T[0..n-1] in {1..K}^n
// require T[n] = T[n+1] = T[n+2] = 0, n >= 2
void suffixArray(int* T, int* SA, int n, int K) {
int n0 = (n + 2) / 3, n1 = (n + 1) / 3, n2 = n / 3, n02 = n0 + n2;
int* R = new int[n02 + 3];
R[n02] = R[n02 + 1] = R[n02 + 2] = 0;
int* SA12 = new int[n02 + 3]; SA12[n02] = SA12[n02 + 1] = SA12[n02 + 2] = 0;
int* R0 = new int[n0];
int* SA0 = new int[n0];
//******* Step 0: Construct sample ********
// generate positions of mod 1 and mod 2 suffixes
// the "+(n0-n1)" adds a dummy mod 1 suffix if n%3 == 1
for (int i = 0, j = 0; i < n + (n0 - n1); i++) if (i%3 != 0) R[j++] = i;
//******* Step 1: Sort sample suffixes ********
// lsb radix sort the mod 1 and mod 2 triples
radixPass(R, SA12, T + 2, n02, K);
radixPass(SA12, R, T + 1, n02, K);
radixPass(R, SA12, T, n02, K);
// find lexicographic names of triples and
// write them to correct places in R
int name = 0, c0 = -1, c1 = -1, c2 = -1;
for (int i = 0; i < n02; i++) {
if (T[SA12[i]] != c0 || T[SA12[i] + 1] != c1 || T[SA12[i] + 2] != c2) {
name++;
c0 = T[SA12[i]];
c1 = T[SA12[i] + 1];
c2 = T[SA12[i] + 2];
}
if (SA12[i] % 3 == 1) {
R[SA12[i] / 3] = name; // write to R1
} else {
R[SA12[i] / 3 + n0] = name; // write to R2
}
}
// recurse if names are not yet unique
if (name < n02) {
suffixArray(R, SA12, n02, name);
// store unique names in R using the suffix array
for (int i = 0; i < n02; i++) R[SA12[i]] = i + 1;
} else // generate the suffix array of R directly
for (int i = 0; i < n02; i++) SA12[R[i] - 1] = i;
//******* Step 2: Sort nonsample suffixes ********
// stably sort the mod 0 suffixes from SA12 by their first character
for (int i = 0, j = 0; i < n02; i++) if (SA12[i] < n0) R0[j++] = 3 * SA12[i];
radixPass(R0, SA0, T, n0, K);
//******* Step 3: Merge ********
// merge sorted SA0 suffixes and sorted SA12 suffixes
for (int p = 0, t = n0 - n1, k = 0; k < n; k++) {
#define GetI() (SA12[t] < n0 ? SA12[t] * 3 + 1 : (SA12[t] - n0) * 3 + 2)
int i = GetI(); // pos of current offset 12 suffix
int j = SA0[p]; // pos of current offset 0 suffix
if (SA12[t] < n0 ? // different compares for mod 1 and mod 2 suffixes
leq(T[i], R[SA12[t] + n0], T[j], R[j / 3]) :
leq(T[i], T[i+1], R[SA12[t] - n0 + 1], T[j], T[j + 1], R[j / 3 + n0])) {
// suffix from SA12 is smaller
SA[k] = i;
t++;
if (t == n02) // done --- only SA0 suffixes left
for (k++; p < n0; p++, k++) SA[k] = SA0[p];
} else { // suffix from SA0 is smaller
SA[k] = j;
p++;
if (p == n0) // done --- only SA12 suffixes left
for (k++; t < n02; t++, k++) SA[k] = GetI();
}
}
delete [] R; delete [] SA12; delete [] SA0; delete [] R0;
}
