This is an easy problem as long as you have done UVA 10196 – Check The Check. I added another “deathByKing” method and just basically used 99% of the old code to solve this problem. The time limit is 3 seconds so a lazy O(N^2) works great.

import java.awt.Point;
import java.io.PrintWriter;
import java.util.Scanner;
import java.util.StringTokenizer;

/**
 *
 * @author Sanchit M. Bhatnagar
 * @see http://uhunt.felix-halim.net/id/74004
 *
 */
public class P10284 {

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    PrintWriter out = new PrintWriter(System.out);
    while (sc.hasNext()) {
      char[][] grid = new char[8][8];
      StringTokenizer st = new StringTokenizer(sc.next(), "/");
      for (int i = 0; i < 8; i++) {
        char[] row = st.nextToken().trim().toCharArray();
        int idx = 0;
        for (Character c : row) {
          if (Character.isDigit(c)) {
            int tmp = c - '0';
            for (int j = idx; j < idx + tmp; j++) {
              grid[i][j] = '.';
            }
            idx += tmp;
          } else {
            grid[i][idx] = c;
            idx++;
          }
        }
      }
      int ans = 0;
      for (int i = 0; i < 8; i++) {
        for (int j = 0; j < 8; j++) {
          if (grid[i][j] == '.') {
            Point tmp = new Point(i, j);
            if (!deathByKing(tmp, grid)) {
              int count = 0;
              grid[i][j] = 'X';
              if (!deathByBishop(tmp, grid) && !deathByKnight(tmp, grid) && !deathByPawn(tmp, grid) && !deathByRook(tmp, grid)) {
                count++;
              }
              grid[i][j] = 'x';
              if (!deathByBishop(tmp, grid) && !deathByKnight(tmp, grid) && !deathByPawn(tmp, grid) && !deathByRook(tmp, grid)) {
                count++;
              }
              grid[i][j] = '.';
              if (count == 2)
                ans++;
            }
          }
        }
      }
      out.println(ans);
    }
    out.close();
    sc.close();
  }

  private static boolean deathByKing(Point king, char[][] grid) {
    int i = king.x;
    int j = king.y;
    for (int n = i - 1; n <= i + 1; n++)
      for (int m = j - 1; m <= j + 1; m++) {
        if (n >= 0 && n < 8 && m >= 0 && m < 8 && (grid[n][m] == 'k' || grid[n][m] == 'K'))
          return true;
      }
    return false;
  }

  private static boolean deathByBishop(Point king, char[][] grid) {
    int i = king.x;
    int j = king.y;
    char thing = '\u000F';
    char thing2 = '\u000F';
    if (Character.isLowerCase(grid[i][j])) {
      // Black King
      thing = 'B';
      thing2 = 'Q';
    } else {
      // White King
      thing = 'b';
      thing2 = 'q';
    }

    // NW
    int idx = i - 1;
    int idx2 = j - 1;
    while (idx >= 0 && idx < 8 && idx2 >= 0 && idx2 < 8 && grid[idx][idx2] == '.') {
      idx--;
      idx2--;
    }
    if (idx >= 0 && idx < 8 && idx2 >= 0 && idx2 < 8 && (grid[idx][idx2] == thing || grid[idx][idx2] == thing2))
      return true;

    // NE
    idx = i - 1;
    idx2 = j + 1;
    while (idx >= 0 && idx < 8 && idx2 >= 0 && idx2 < 8 && grid[idx][idx2] == '.') {
      idx--;
      idx2++;
    }
    if (idx >= 0 && idx < 8 && idx2 >= 0 && idx2 < 8 && (grid[idx][idx2] == thing || grid[idx][idx2] == thing2))
      return true;

    // SW
    idx = i + 1;
    idx2 = j - 1;
    while (idx >= 0 && idx < 8 && idx2 >= 0 && idx2 < 8 && grid[idx][idx2] == '.') {
      idx++;
      idx2--;
    }
    if (idx >= 0 && idx < 8 && idx2 >= 0 && idx2 < 8 && (grid[idx][idx2] == thing || grid[idx][idx2] == thing2))
      return true;

    // RIGHT
    idx = i + 1;
    idx2 = j + 1;
    while (idx >= 0 && idx < 8 && idx2 >= 0 && idx2 < 8 && grid[idx][idx2] == '.') {
      idx++;
      idx2++;
    }
    if (idx >= 0 && idx < 8 && idx2 >= 0 && idx2 < 8 && (grid[idx][idx2] == thing || grid[idx][idx2] == thing2))
      return true;

    return false;
  }

  private static boolean deathByRook(Point king, char[][] grid) {
    int i = king.x;
    int j = king.y;
    char thing = '\u000F';
    char thing2 = '\u000F';
    if (Character.isLowerCase(grid[i][j])) {
      // Black King
      thing = 'R';
      thing2 = 'Q';
    } else {
      // White King
      thing = 'r';
      thing2 = 'q';
    }

    // UP
    int idx = i - 1;
    while (idx >= 0 && grid[idx][j] == '.') {
      idx--;
    }
    if (idx >= 0 && idx < 8 && (grid[idx][j] == thing || grid[idx][j] == thing2))
      return true;

    // DOWN
    idx = i + 1;
    while (idx < 8 && grid[idx][j] == '.') {
      idx++;
    }
    if (idx >= 0 && idx < 8 && (grid[idx][j] == thing || grid[idx][j] == thing2))
      return true;

    // LEFT
    idx = j - 1;
    while (idx >= 0 && grid[i][idx] == '.') {
      idx--;
    }
    if (idx >= 0 && idx < 8 && (grid[i][idx] == thing || grid[i][idx] == thing2))
      return true;

    // RIGHT
    idx = j + 1;
    while (idx < 8 && grid[i][idx] == '.') {
      idx++;
    }
    if (idx >= 0 && idx < 8 && (grid[i][idx] == thing || grid[i][idx] == thing2))
      return true;

    return false;
  }

  private static boolean deathByKnight(Point king, char[][] grid) {
    int i = king.x;
    int j = king.y;
    char thing = '\u000F';
    if (Character.isLowerCase(grid[i][j])) {
      // Black King
      thing = 'N';
    } else {
      // White King
      thing = 'n';
    }
    if (i + 2 < 8) {
      if (j - 1 >= 0 && grid[i + 2][j - 1] == thing)
        return true;
      if (j + 1 < 8 && grid[i + 2][j + 1] == thing)
        return true;
    }
    if (i - 2 >= 0) {
      if (j - 1 >= 0 && grid[i - 2][j - 1] == thing)
        return true;
      if (j + 1 < 8 && grid[i - 2][j + 1] == thing)
        return true;
    }
    if (j + 2 < 8) {
      if (i - 1 >= 0 && grid[i - 1][j + 2] == thing)
        return true;
      if (i + 1 < 8 && grid[i + 1][j + 2] == thing)
        return true;
    }
    if (j - 2 >= 0) {
      if (i - 1 >= 0 && grid[i - 1][j - 2] == thing)
        return true;
      if (i + 1 < 8 && grid[i + 1][j - 2] == thing)
        return true;
    }

    return false;
  }

  private static boolean deathByPawn(Point king, char[][] grid) {
    int i = king.x;
    int j = king.y;
    char thing = '\u000F';
    if (Character.isLowerCase(grid[i][j])) {
      // Black King
      i++;
      thing = 'P';
    } else {
      // White King
      i--;
      thing = 'p';
    }
    if (i >= 0 && i < 8) {
      if (j - 1 >= 0 && grid[i][j - 1] == thing)
        return true;
      if (j + 1 < 8 && grid[i][j + 1] == thing)
        return true;
    }
    return false;
  }
}