LeetCodeWordSearchProblem

class Solution {
    char[][] board;
    public boolean exist(char[][] board, String word){
        this.board = board;
        //exist(0,0, word);
        for(int i = 0; i<board.length; i++){
            for(int j = 0; j<board[i].length; j++){
                if(exist(i, j, word)){
                    return true;
                }
            }
        }
        return false;
    }
    boolean isValidPath = false;
    public boolean exist(int row, int col, String word) {
        // word found
        if(word.length() ==0){
            return true;
        }
        // if word not found and goes out of range
        if(row<0 || col<0 || row == board.length || col==board[row].length || board[row][col]!=word.charAt(0)){
            return false;
        }
        // Mark as Visited
        board[row][col] = '#'; // Mark as visited.
        // Lookup in all 4 Directions
        int directions [][] = {
            {0,1},// right
            {1,0},// down
            {-1,0},// up
            {0,-1} // left
        };
        for(int direction =0; direction<directions.length; direction++){
            int rowDirection = directions[direction][0]; // get row
            int colDirection = directions[direction][1]; // get col
            isValidPath = exist(row + rowDirection, col + colDirection, word.substring(1));
            if(isValidPath){
                break;
            }
        }
        // BackTracking (Undo)
        board[row][col] = word.charAt(0);
        return isValidPath;
        
    }
}