In this HackerEarth Unique Gems problem solution Rahul has entered into a mysterious land of gems. There is a record S for each of the gems that is maintained in form of a string. Each gem is characterized by some substring of this string. Interestingly, the number of occurrences of a sub-string in S is the exact number of such gems present in the land.

However, Rahul is only interested in unique gems. Please tell the number of such sub-strings that occur exactly once.

HackerEarth Unique Gems problem solution


HackerEarth Unique Gems problem solution.

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.Arrays;
import java.io.BufferedWriter;
import java.util.InputMismatchException;
import java.util.Comparator;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.io.InputStream;

public class Main {
public static void main(String[] args) {
InputStream inputStream = System.in;
OutputStream outputStream = System.out;
InReader in = new InReader(inputStream);
OutputWriter out = new OutputWriter(outputStream);
TwoRepetitions solver = new TwoRepetitions();
int testCount = Integer.parseInt(in.next());
for (int i = 1; i <= testCount; i++)
solver.solve(i, in, out);
out.close();
}
}

class TwoRepetitions {
public void solve(int testNumber, InReader in, OutputWriter out) {
String s = in.readString();
int n = s.length();
int[] sa = SuffixArray.suffixArray(s);
int[] lcp = SuffixArray.lcp(sa, s);
int last = 0;
long ans = 0;
long dis = 1L * n * (n + 1L) / 2;
for (int l : lcp) {
int add = l - last;
if(add > 0) ans += add;
last = l;
dis -= l;
}
out.printLine(dis - ans);
}
}

class InReader {

private InputStream stream;
private byte[] buf = new byte[1024];
private int curChar;
private int numChars;
private SpaceCharFilter filter;

public InReader(InputStream stream) {
this.stream = stream;
}

public static boolean isWhitespace(int c) {
return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
}

public int read() {
if (numChars == -1)
throw new InputMismatchException();
if (curChar >= numChars) {
curChar = 0;
try {
numChars = stream.read(buf);
} catch (IOException e) {
throw new InputMismatchException();
}
if (numChars <= 0)
return -1;
}
return buf[curChar++];
}

public int readInt() {
int c = read();
while (isSpaceChar(c))
c = read();
int sgn = 1;
if (c == '-') {
sgn = -1;
c = read();
}
int res = 0;
do {
if (c < '0' || c > '9')
throw new InputMismatchException();
res *= 10;
res += c - '0';
c = read();
} while (!isSpaceChar(c));
return res * sgn;
}

public long readLong() {
int c = read();
while (isSpaceChar(c))
c = read();
int sgn = 1;
if (c == '-') {
sgn = -1;
c = read();
}
long res = 0;
do {
if (c < '0' || c > '9')
throw new InputMismatchException();
res *= 10;
res += c - '0';
c = read();
} while (!isSpaceChar(c));
return res * sgn;
}

public String readString() {
int c = read();
while (isSpaceChar(c))
c = read();
StringBuffer res = new StringBuffer();
do {
res.appendCodePoint(c);
c = read();
} while (!isSpaceChar(c));
return res.toString();
}

public boolean isSpaceChar(int c) {
if (filter != null)
return filter.isSpaceChar(c);
return isWhitespace(c);
}

public String next() {
return readString();
}

public interface SpaceCharFilter {
public boolean isSpaceChar(int ch);
}
}

class OutputWriter {
private final PrintWriter writer;

public OutputWriter(OutputStream outputStream) {
writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
}

public OutputWriter(Writer writer) {
this.writer = new PrintWriter(writer);
}

public void print(Object... objects) {
for (int i = 0; i < objects.length; i++) {
if (i != 0)
writer.print(' ');
writer.print(objects[i]);
}
}


public void printLine(Object... objects) {
print(objects);
writer.println();
}

public void close() {
writer.close();
}

}

class SuffixArray {
public static int[] suffixArray(final CharSequence str) {
int n = str.length();
Integer[] order = new Integer[n];
for (int i = 0; i < n; i++)
order[i] = n - 1 - i;

Arrays.sort(order, new Comparator<Integer>() {
@Override
public int compare(Integer o1, Integer o2) {
return Character.compare(str.charAt(o1), str.charAt(o2));
}
});
int[] sa = new int[n];
int[] rank = new int[n];
for (int i = 0; i < n; i++) {
sa[i] = order[i];
rank[i] = str.charAt(i);
}

for (int len = 1; len < n; len *= 2) {
int[] r = rank.clone();
for (int i = 0; i < n; i++) {
rank[sa[i]] = i > 0 && r[sa[i - 1]] == r[sa[i]] && sa[i - 1] + len < n && r[sa[i - 1] + len / 2] == r[sa[i] + len / 2] ? rank[sa[i - 1]] : i;
}
int[] cnt = new int[n];
for (int i = 0; i < n; i++)
cnt[i] = i;
int[] s = sa.clone();
for (int i = 0; i < n; i++) {
int s1 = s[i] - len;
if (s1 >= 0)
sa[cnt[rank[s1]]++] = s1;
}
}
return sa;
}
public static int[] lcp(int[] sa, CharSequence s) {
int n = sa.length;
int[] rank = new int[n];
for (int i = 0; i < n; i++)
rank[sa[i]] = i;
int[] lcp = new int[n - 1];
for (int i = 0, h = 0; i < n; i++) {
if (rank[i] < n - 1) {
int j = sa[rank[i] + 1];
while (Math.max(i, j) + h < s.length() && s.charAt(i + h) == s.charAt(j + h)) {
++h;
}
lcp[rank[i]] = h;
if (h > 0)
--h;
}
}
return lcp;
}
}

Second solution

#include <cstdio>
#include <cmath>
#include <iostream>
#include <set>
#include <algorithm>
#include <vector>
#include <map>
#include <cassert>
#include <string>
#include <cstring>
#include <queue>

using namespace std;

#define rep(i,a,b) for(int i = a; i < b; i++)
#define S2(x,y) scanf("%d%d",&x,&y)
#define P(x) printf("%d\n",x)
#define all(v) v.begin(),v.end()
#define sz size()
#define F first
#define S second

typedef long long int LL;
typedef pair<int, int > pii;
typedef vector<int > vi;

const int N = 100001;

string s;
vector<pii > ranks;

pair<int, pii > v[N];
int tag[N][22];
int mxPow;
int n;

void buildSA(string &s) {
n = s.sz;
rep(i,0,n) {
v[i].F = s[i] - 'a' + 1;
v[i].S.F = -1;
v[i].S.S = i;
tag[i][0] = v[i].F;
}

int len = 1;
int j = 0;
while(len < n) {
len += len;
j++;

rep(i,0,n) {
v[i].F = tag[i][j-1];
if(i+len/2 < n) v[i].S.F = tag[i+len/2][j-1];
else v[i].S.F = -1;
v[i].S.S = i;
}
sort(v, v+n);

int tagId = 1;
tag[v[0].S.S][j] = 1;
rep(i,1,n) {
if(v[i].F != v[i-1].F || v[i].S.F != v[i-1].S.F) {
tagId++;
}
tag[v[i].S.S][j] = tagId;
}
}
mxPow = j;
}

int lcp(int x, int y) {

int res = 0;
for(int i = mxPow; i >= 0; i--) {
if(tag[x][i] == tag[y][i]) {
res += 1 << i;
x += 1 << i;
y += 1 << i;
}
if(x >= n || y >= n) break;
}
return res;
}

int main() {
int t;
cin >> t;
assert(t >= 1 && t <= 10);
while(t--) {
cin >> s;
buildSA(s);
int n = s.sz;
assert(n > 0 && n <= 100000);

ranks.clear();
rep(i,0,n) {
ranks.push_back(make_pair(tag[i][mxPow], i));
}
sort(all(ranks));

LL ans = 0;
rep(i,0,n) {
int mx = 0;
if(i-1 >= 0) mx = max(mx, lcp(ranks[i-1].S, ranks[i].S));
if(i+1 < n) mx = max(mx, lcp(ranks[i+1].S, ranks[i].S));
// P(mx);

ans += n - ranks[i].S - mx;
}
cout << ans << endl;
}
return 0;
}