[Java] HackerRank_Java 1D Array (Part 2)

[Problem]

Let's play a game on an array! You're standing at index 0 of an n-element array named game. From some index i (where 0 ≤ i < n), you can perform one of the following moves:

• Move Backward: If cell i - 1 exists and contains a 0, you can walk back to cell i - 1.
• Move Forward:
  • If cell i + 1 contains a zero, you can walk to cell i + 1.
  • If cell i + leap contains a zero, you can jump to cell i + leap.
  • If you're standing in cell n - 1 or the value of i + leap ≥ n, you can walk or jump off the end of the array and win the game.

In other words, you can move from index i to index i + 1, i - 1, or i + leap as long as the destination index is a cell containing a 0. If the destination index is greater than n - 1, you win the game.

Given leap and game, complete the function in the editor below so that it returns true if you can win the game (or false if you cannot).

Input Format

The first line contains an integer, q, denoting the number of queries (i.e., function calls).
The 2 * q subsequent lines describe each query over two lines:

1. The first line contains two space-separated integers describing the respective values of n and leap.
2. The second line contains n space-separated binary integers (i.e., zeroes and ones) describing the respective values of game₀, game₁, ..., game_n-1.

Constraints

• 1 ≤ q ≤5000
• 2 ≤ n ≤100
• 0 ≤ leap ≤100
• It is guaranteed that the value of game[0] is always 0.

Output Format

Return true if you can win the game; otherwise, return false.

Sample Input

4

5 3

0 0 0 0 0

6 5

0 0 0 1 1 1

6 3

0 0 1 1 1 0

3 1

0 1 0

Sample Output

YES

YES

NO

NO

Explanation

We perform the following q = 4 queries:

1. For game = [0, 0, 0, 0, 0] and leap = 3, we can walk and/or jump to the end of the array because every cell contains a 0. Because we can win, we return true.
2. For game = [0, 0, 0, 1, 1, 1] and leap = 5, we can walk to index 1 and then jump i + leap = 1 + 5 = 6 units to the end of the array. Because we can win, we return true.
3. For game = [0, 0, 1, 1, 1, 0] and leap = 3, there is no way for us to get past the three consecutive ones. Because we cannot win, we return false.
4. For game = [0, 1, 0] and leap = 1, there is no way for us to get past the one at index 1. Because we cannot win, we return false.

[Solution]

import java.util.*;

public class Solution {

    public static boolean canWin(int leap, int[] game) {
        // Return true if you can win the game; otherwise, return false.
        int position = 0;
        int destination = game.length - 1;
        List<List<Integer>> node = new ArrayList<>();
        for ( int i = 0; i <= destination; ++i ) {
            node.add(new ArrayList<>());
            if ( i + 1 <= destination ) {
                node.get(i).add(i + 1);
            } else {
                node.get(i).add(-1);
            }
            if ( i - 1 >= 0 ) {
                node.get(i).add(i - 1);
            }
            if ( i + leap <= destination ) {
                node.get(i).add(i + leap);
            } else {
                node.get(i).add(-1);
            }
        }
        boolean[] isVisited = new boolean[game.length];
        for ( int i = 0; i < isVisited.length; ++i ) {
            isVisited[i] = false;
        }
        Queue<Integer> queue = new LinkedList<Integer>();
        queue.add(0);
        
        while ( !queue.isEmpty() ) {
            int currentNode = queue.poll();
            isVisited[currentNode] = true;
            for ( Integer n: node.get(currentNode) ) {
                if ( n == -1 ) {
                    return true;
                }
                if ( n >= 0 && !isVisited[n] ) {
                    if ( game[n] == 0 ) {
                        queue.add(n);
                    }
                }
            }
        }
        return false;
    }

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int q = scan.nextInt();
        while (q-- > 0) {
            int n = scan.nextInt();
            int leap = scan.nextInt();
            
            int[] game = new int[n];
            for (int i = 0; i < n; i++) {
                game[i] = scan.nextInt();
            }

            System.out.println( (canWin(leap, game)) ? "YES" : "NO" );
        }
        scan.close();
    }
}