Submission #923965

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Source Code Expand

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
import java.util.function.BiFunction;

public class Main {
  Scanner sc = new Scanner(System.in);

  public static void main(String[] args) {
    new Main().run();
  }

  int[][] ofs = {
      {-1, 0},
      {0, -1},
      {0, 1},
      {1, 0}
  };

  int h, w;
  int[][] field;
  long MOD = 1_000_000_007;

  long[][] dp;
  boolean[][] done;

  long dfs(int x, int y) {
    if (done[y][x]) {
      return dp[y][x];
    }
    long sum = 1;
    for (int i = 0; i < 4; ++i) {
      int nx = x + ofs[i][0];
      int ny = y + ofs[i][1];
      if (field[ny][nx] == 0) {
        continue;
      }
      if (field[y][x] >= field[ny][nx]) {
        continue;
      }
      sum += dfs(nx, ny);
      sum %= MOD;
    }
    dp[y][x] = sum;
    done[y][x] = true;
    return sum;
  }

  void run() {
    int h = ni();
    int w = ni();
    field = new int[h + 2][w + 2];
    dp = new long[h + 2][w + 2];
    done = new boolean[h + 2][w + 2];
    for (int i = 1; i <= h; ++i) {
      for (int j = 1; j <= w; ++j) {
        field[i][j] = ni();
      }
    }
    long sum = 0;
    for (int i = 1; i <= h; ++i) {
      for (int j = 1; j <= w; ++j) {
        sum += dfs(j, i);
        sum %= MOD;
      }
    }
    System.out.println(sum);
  }

  int ni() {
    return Integer.parseInt(sc.next());
  }

  void debug(Object... os) {
    System.err.println(Arrays.deepToString(os));
  }

  class BIT<T> {
    int n;
    ArrayList<T> bit;
    BiFunction<T, T, T> bif;

    BIT(int n, BiFunction<T, T, T> bif, T defaultValue) {
      this.n = n;
      bit = new ArrayList<>(n + 1);
      for (int i = 0; i < n + 1; ++i) {
        bit.add(defaultValue);
      }
      this.bif = bif;
    }

    void update(int i, T v) {
      for (int x = i; x <= n; x += x & -x) {
        bit.set(x, bif.apply(bit.get(x), v));
      }
    }

    T reduce(int i, T defaultValue) {
      T ret = defaultValue;
      for (int x = i; x > 0; x -= x & -x) {
        ret = bif.apply(ret, bit.get(x));
      }
      return ret;
    }
  }
}

Submission Info

Judge Result