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天下一プログラマーコンテスト2014予選A C - 天下一文字列集合

解法

bitDP

コード

package atcoder.tenka12014quala;

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

public class C {
  private static class Task {
    void solve(FastScanner in, PrintWriter out) {
      int N = in.nextInt();
      int M = in.nextInt();
      char[][] str = new char[N][];
      for (int i = 0; i < N; i++) str[i] = in.next().toCharArray();
      boolean[][] map = new boolean[N][N];
      for (int i = 0; i < N; i++) map[i][i] = true;
      for (int i = 0; i < N; i++) {
        for (int j = i + 1; j < N; j++) {
          boolean ok = true;
          for (int m = 0; m < M; m++) {
            if (str[i][m] != str[j][m] && str[i][m] != '*' && str[j][m] != '*') {
              ok = false;
              break;
            }
          }
          if (ok) {
            map[i][j] = true;
            map[j][i] = true;
          }
        }
      }

      int[] dp = new int[1 << N];
      for (int mask = 0; mask < (1 << N); mask++) {
        boolean ok = true;
        check:
        for (int i = 0; i < N; i++) {
          if ((mask & (1 << i)) == 0) continue;
          for (int j = i + 1; j < N; j++) {
            if ((mask & (1 << j)) == 0) continue;
            if (!map[i][j]) {
              ok = false;
              break check;
            }
          }
        }
        if (ok) {
          dp[mask] = 1;
          continue;
        }

        int min = Integer.bitCount(mask);
        for (int subMask = 1; subMask < mask; subMask++) {
          if ((subMask & mask) != subMask) continue;
          min = Math.min(min, dp[subMask] + dp[mask - subMask]);
        }
        dp[mask] = min;
      }
      out.println(dp[(1 << N) - 1]);

    }
  }

  // Template
  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;
    }
  }
}