How to count all occurrences of a word in a character matrix?

Question

Problem

Given a m x n 2D board of characters and a word, find how many times the word is present in the board.

The word can be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or vertically neighboring.

Note: The same letter cell may not be used more than once.

Input Format

First line contains two space separated integers m, n that denotes the number of rows and columns in the board respectively. Next m lines contain n characters each. Last line contains the word to be searched.

Constraints

1 <= m, n <= 5

1 <= lengthOf(word) <= 30

enter code here

Output Format

Print the total count of the given word in the 2-D board.

Sample Input

3 4
HDST
ANEO
BENY
NEST  // word

Sample Output

Also I am not able to satisfy the test case

5 5
LACOO 
OOOCL
NLOOO
ECOCO
MECOO
COOLOOC

Output should be

My Code

 public static void main(String[] args) {
        int m, n;
        Scanner sc = new Scanner(System.in);
        m = sc.nextInt();
        n = sc.nextInt();

        char[][] board = new char[m][n + 1];
        for (int i = 0; i < m; i++) {
            String temp = sc.next();
            board[i] = temp.toCharArray();
        }

        String word = sc.next();

        System.out.print(new Result().countWord(board, word, m, n));
    }

static class Result {
        static boolean[][] visited;
        static int count = 0;

        int countWord(char board[][], String word, int m, int n) {
            visited = new boolean[m][n];
            for (int i = 0; i < m; i++) {
                for (int j = 0; j < n; j++) {
                    if (board[i][j] == word.charAt(0)) {
                        if(searchWord(board, word, i, j, m, n, 0))
                            count++;
                    }
                }
            }
            return count;
        }

        static boolean searchWord(char board[][], String word, int i, int j, int m, int n, int index) {
            if (index == word.length()) {
                count++;
                return true;
            }

            if (i < 0 || j < 0 || i >= m || j >= n)
                return false;

            if (visited[i][j] || board[i][j] != word.charAt(index))
                return false;

            visited[i][j] = true;

            if (searchWord(board, word, i - 1, j, m, n, index + 1) ||
                    searchWord(board, word, i + 1, j, m, n, index + 1) ||
                    searchWord(board, word, i, j - 1, m, n, index + 1) ||
                    searchWord(board, word, i, j + 1, m, n, index + 1)) {
                return true;
            }

            visited[i][j] = false;
            return false;
        }
    }

Could you also share the main? It helps us to test. – Mr. Brickowski May 03 '22 at 08:34 — Mr. Brickowski, May 03 '22 at 08:34

score 2 · Accepted Answer · answered May 03 '22 at 08:42

I think your problem is that you return all calls if you find your word. However, even if you found one word you still want to search all other possibilities because the word you search for can occur multiple times starting from the same cell.

Therefore, I suggest removing the boolean return value from the dfs function as you still want to search for other possibilities if you found the word. I tested following code with your example inputs and it seems to work.

static void searchWord(char board[][], String word, int i, int j, int m, int n, int index) {

    if (i < 0 || j < 0 || i >= m || j >= n)
        return;

    if (visited[i][j] || board[i][j] != word.charAt(index))
        return;

    if (index + 1 == word.length()) {
        count++;
        return;
    }

    visited[i][j] = true;

    searchWord(board, word, i - 1, j, m, n, index + 1);
    searchWord(board, word, i + 1, j, m, n, index + 1);
    searchWord(board, word, i, j - 1, m, n, index + 1);
    searchWord(board, word, i, j + 1, m, n, index + 1);

    visited[i][j] = false;
}

EDIT: I also had to change the order of your if statements as you otherwise would count each occurrence four times.

Thanks a lot.I completely understood it and now all test cases are running fine.Thanks again — Anonymous, May 03 '22 at 09:06

How to count all occurrences of a word in a character matrix?

Problem

1 Answers1