Jump Game III

Given an array of non-negative integers arr, you are initially positioned at start index of the array. When you are at index i, you can jump to i + arr[i] or i - arr[i], check if you can reach to any index with value 0.

Notice that you can not jump outside of the array at any time.

Example 1:

Input: arr = [4,2,3,0,3,1,2], start = 5
Output: true
Explanation: 
All possible ways to reach at index 3 with value 0 are: 
index 5 -> index 4 -> index 1 -> index 3 
index 5 -> index 6 -> index 4 -> index 1 -> index 3 

Example 2:

Input: arr = [4,2,3,0,3,1,2], start = 0
Output: true 
Explanation: 
One possible way to reach at index 3 with value 0 is: 
index 0 -> index 4 -> index 1 -> index 3

Example 3:

Input: arr = [3,0,2,1,2], start = 2
Output: false
Explanation: There is no way to reach at index 1 with value 0.

Constraints:

• 1 <= arr.length <= 5 * 10^4

• 0 <= arr[i] < arr.length

• 0 <= start < arr.length

class Solution {
    public boolean backtrack(int[] arr, int start, boolean[] visited) {
        if (start < 0 || start >= visited.length || visited[start])
            return false;
        if (arr[start] == 0)
            return true;
        visited[start] = true;
        boolean ans = backtrack(arr, start + arr[start], visited) || backtrack(arr, start - arr[start], visited);
        visited[start] = false;
        return ans;
    }

    public boolean canReach(int[] arr, int start) {
        boolean[] visited = new boolean[arr.length];
        return backtrack(arr, start, visited);
    }
}