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path: root/src/main/HashSubstring.java
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import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
import java.util.concurrent.ThreadLocalRandom;

public class HashSubstring {

    private static FastScanner in;
    private static PrintWriter out;

    public static void main(String[] args) throws IOException {
        in = new FastScanner();
        out = new PrintWriter(new BufferedOutputStream(System.out));
        printOccurrences(rabinKarp(readInput()));
        out.close();
    }

    private static Data readInput() throws IOException {
        String pattern = in.next();
        String text = in.next();
        return new Data(pattern, text);
    }

    private static void printOccurrences(List<Integer> ans) {
        for (Integer cur : ans) {
            out.print(cur);
            out.print(" ");
        }
    }

    static List<Integer> getOccurrences(Data input) {
        String s = input.pattern, t = input.text;
        int m = s.length(), n = t.length();
        List<Integer> occurrences = new ArrayList<>();
        for (int i = 0; i + m <= n; ++i) {
            boolean equal = true;
            for (int j = 0; j < m; ++j) {
                if (s.charAt(j) != t.charAt(i + j)) {
                    equal = false;
                    break;
                }
            }
            if (equal)
                occurrences.add(i);
        }
        return occurrences;
    }

    static class Data {
        String pattern;
        String text;

        Data(String pattern, String text) {
            this.pattern = pattern;
            this.text = text;
        }
    }

    static long polyHash(String S, int p, int x) {
        long hash = 0;

        for (int i = S.length() - 1; i >= 0; --i)
            hash = (hash * x + S.charAt(i)) % p;

        return hash;
    }

    static long[] preComputeHashes(String T, int pattenLength, int p, int x) {
        long[] H = new long[T.length() - pattenLength + 1];
        String S = T.substring(T.length() - pattenLength);
        H[T.length() - pattenLength] = polyHash(S, p, x);
        long y = 1;
        for (int i = 0; i < pattenLength; i++) {
            y = (y * x) % p;
        }
        for (int i = T.length() - pattenLength - 1; i >= 0; --i) {
            H[i] = (x * H[i + 1] + T.charAt(i) - y * T.charAt(i + pattenLength)) % p;
        }
        return H;
    }

    static List<Integer> rabinKarp(Data input) {
        String T = input.text;
        String P = input.pattern;
        int p = 1000000007;
        int x = ThreadLocalRandom.current().nextInt(1, p);
        List<Integer> positions = new ArrayList<>();
        long pHash = polyHash(P, p, x);
        long[] H = preComputeHashes(T, P.length(), p, x);
        for (int i = 0; i < T.length() - P.length() + 1; i++) {
            if (pHash != H[i]) {
                continue;
            }
            if (T.substring(i, i + P.length()).equals(P))
                positions.add(i);
        }
        return positions;
    }

    static List<Integer> rabinKarp(String P, String T) {
        int p = 1000000007;
        int x = ThreadLocalRandom.current().nextInt(1, p);
        List<Integer> positions = new ArrayList<>();
        long pHash = polyHash(P, p, x);
        long[] H = preComputeHashes(T, P.length(), p, x);
        for (int i = 0; i < T.length() - P.length() + 1; i++) {
            if (pHash != H[i]) {
                continue;
            }
            if (T.substring(i, i + P.length()).equals(P))
                positions.add(i);
        }
        return positions;
    }

    static class FastScanner {
        private BufferedReader reader;
        private StringTokenizer tokenizer;

        FastScanner() {
            reader = new BufferedReader(new InputStreamReader(System.in));
            tokenizer = null;
        }

        String next() throws IOException {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                tokenizer = new StringTokenizer(reader.readLine());
            }
            return tokenizer.nextToken();
        }
    }
}