天下一プログラマーコンテスト2016本戦 C - たんごたくさん

問題

C: たんごたくさん - 天下一プログラマーコンテスト2016本戦（オープンコンテスト） | AtCoder

解法

文字列 S の位置 pos を見ている時、 [pos..pos+l) と一致する長さ l の単語を列挙する。l の最大値は 200 なので、列挙される単語もたかだか 200 個しかない。

Trie 木を作って単語の列挙を効率的に行い、遷移が最大 200 通りの dp をすれば良い。

コード

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.NoSuchElementException;

/*
                   _ooOoo_
                  o8888888o
                  88" . "88
                  (| -_- |)
                  O\  =  /O
               ____/`---'\____
             .'  \\|     |//  `.
            /  \\|||  :  |||//  \
           /  _||||| -:- |||||-  \
           |   | \\\  -  /// |   |
           | \_|  ''\---/''  |   |
           \  .-\__  `-`  ___/-. /
         ___`. .'  /--.--\  `. . __
      ."" '<  `.___\_<|>_/___.'  >'"".
     | | :  `- \`.;`\ _ /`;.`/ - ` : | |
     \  \ `-.   \_ __\ /__ _/   .-` /  /
======`-.____`-.___\_____/___.-`____.-'======
                   `=---='
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            pass System Test!
*/

public class Main {
  private static class Task {
    class Trie {
      class Node {
        int[] to = new int[26];
        int weight = 0;
      }

      ArrayList<Node> nodes = new ArrayList<>();
      Trie() {
        nodes.add(new Node());
      }

      void add(char[] s, int weight) {
        recursiveAdd(0, 0, s, weight);
      }

      void recursiveAdd(int n, int pos, char[] s, int weight) {
        Node node = nodes.get(n);
        if (pos == s.length) {
          node.weight = weight;
          return;
        }
        int c = s[pos] - 'a';
        if (node.to[c] == 0) {
          Node next = new Node();
          node.to[c] = nodes.size();
          nodes.add(next);
        }
        recursiveAdd(node.to[c], pos + 1, s, weight);
      }

      ArrayList<int[]> getDestinations(int pos, char[] S) {
        ArrayList<int[]> list = new ArrayList<>();
        recursiveGet(0, pos, 0, S, list);
        return list;
      }

      void recursiveGet(int n, int pos, int length, char[] S, ArrayList<int[]> list) {
        Node node = nodes.get(n);
        if (node.weight > 0) list.add(new int[]{length, node.weight});
        if (pos == S.length) return;
        int c = S[pos] - 'a';
        if (node.to[c] == 0) return;
        recursiveGet(node.to[c], pos + 1, length + 1, S, list);
      }

    }

    void solve(FastScanner in, PrintWriter out) {
      char[] S = in.next().toCharArray();
      int N = S.length;
      int M = in.nextInt();
      char[][] P = new char[M][];
      for (int i = 0; i < M; i++) P[i] = in.next().toCharArray();
      int[] W = new int[M];
      for (int i = 0; i < M; i++) W[i] = in.nextInt();

      Trie trie = new Trie();
      for (int i = 0; i < M; i++) {
        trie.add(P[i], W[i]);
      }
      long[] dp = new long[N + 1];
      for (int pos = 0; pos < N; pos++) {
        for (int[] dw : trie.getDestinations(pos, S)) {
          dp[pos + dw[0]] = Math.max(dp[pos + dw[0]], dp[pos] + dw[1]);
        }
        dp[pos + 1] = Math.max(dp[pos + 1], dp[pos]);
      }
      out.println(dp[N]);
    }
  }

  /**
   * ここから下はテンプレートです。
   */
  public static void main(String[] args) {
    OutputStream outputStream = System.out;
    FastScanner in = new FastScanner();
    PrintWriter out = new PrintWriter(outputStream);
    Task solver = new Task();
    solver.solve(in, out);
    out.close();
  }
  private static class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int bufferLength = 0;

    private boolean hasNextByte() {
      if (ptr < bufferLength) {
        return true;
      } else {
        ptr = 0;
        try {
          bufferLength = in.read(buffer);
        } catch (IOException e) {
          e.printStackTrace();
        }
        if (bufferLength <= 0) {
          return false;
        }
      }
      return true;
    }

    private int readByte() {
      if (hasNextByte()) return buffer[ptr++];
      else return -1;
    }

    private static boolean isPrintableChar(int c) {
      return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
      while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
    }

    boolean hasNext() {
      skipUnprintable();
      return hasNextByte();
    }

    public String next() {
      if (!hasNext()) throw new NoSuchElementException();
      StringBuilder sb = new StringBuilder();
      int b = readByte();
      while (isPrintableChar(b)) {
        sb.appendCodePoint(b);
        b = readByte();
      }
      return sb.toString();
    }

    long nextLong() {
      if (!hasNext()) throw new NoSuchElementException();
      long n = 0;
      boolean minus = false;
      int b = readByte();
      if (b == '-') {
        minus = true;
        b = readByte();
      }
      if (b < '0' || '9' < b) {
        throw new NumberFormatException();
      }
      while (true) {
        if ('0' <= b && b <= '9') {
          n *= 10;
          n += b - '0';
        } else if (b == -1 || !isPrintableChar(b)) {
          return minus ? -n : n;
        } else {
          throw new NumberFormatException();
        }
        b = readByte();
      }
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    double[] nextDoubleArray(int n) {
      double[] array = new double[n];
      for (int i = 0; i < n; i++) {
        array[i] = nextDouble();
      }
      return array;
    }

    double[][] nextDoubleMap(int n, int m) {
      double[][] map = new double[n][];
      for (int i = 0; i < n; i++) {
        map[i] = nextDoubleArray(m);
      }
      return map;
    }

    public int nextInt() {
      return (int) nextLong();
    }

    public int[] nextIntArray(int n) {
      int[] array = new int[n];
      for (int i = 0; i < n; i++) array[i] = nextInt();
      return array;
    }

    public long[] nextLongArray(int n) {
      long[] array = new long[n];
      for (int i = 0; i < n; i++) array[i] = nextLong();
      return array;
    }

    public String[] nextStringArray(int n) {
      String[] array = new String[n];
      for (int i = 0; i < n; i++) array[i] = next();
      return array;
    }

    public char[][] nextCharMap(int n) {
      char[][] array = new char[n][];
      for (int i = 0; i < n; i++) array[i] = next().toCharArray();
      return array;
    }

    public int[][] nextIntMap(int n, int m) {
      int[][] map = new int[n][];
      for (int i = 0; i < n; i++) {
        map[i] = nextIntArray(m);
      }
      return map;
    }
  }
}