# Jump Game Microsoft OA 2023

## Jump Game Solution

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 * 104
• 0 <= arr[i] < arr.length
• 0 <= start < arr.length

### SOLUTION

Program: Jump Game Solution in Python

``````class Solution:
def canReach(self, arr: List[int], start: int) -> bool:
import collections
queue=collections.deque()
queue.append(start)
s=set()

while len(queue):
curr = queue.popleft()

if arr[curr]==0:
return True

if curr not in s:
if curr + arr[curr] < len(arr):
queue.append(curr + arr[curr])
if curr - arr[curr] > -1:
queue.append(curr - arr[curr])

return False``````

Program: Jump Game Solution in Python

``````class Solution:
def canReach(self, arr: List[int], start: int) -> bool:
seen, temp = set(), [start]
while temp:
i = temp.pop()
if arr[i] == 0: return True
if 0 <= i - arr[i] < len(arr) and i - arr[i] not in seen:
temp.append(i - arr[i])
if 0 <= i + arr[i] < len(arr) and i + arr[i] not in seen:
temp.append(i + arr[i])
return False``````

Program: Jump Game Solution in Java

``````/*
Classic DFS question.
For DFS loops, modify the arr value to go beyound valid as "visited".
*/
class Solution {
public boolean canReach(int[] arr, int start) {
if (start < 0 || start >= arr.length || arr[start] >= arr.length) {
return false;
}
if (arr[start] == 0) {
return true;
}
int move = arr[start];
arr[start] = arr.length;
return canReach(arr, start - move) || canReach(arr, start + move);
}
}``````

Program: Jump Game Solution in C++

``````class Solution {
public:
int solve(vector<int>& arr, int idx){
if(idx<0 || idx>arr.size()-1 || arr[idx]==-100) return 0;
if(arr[idx]==0) return 1;
int temp = arr[idx];
arr[idx]=-100;
bool right = solve(arr,idx+temp);
bool left = solve(arr,idx-temp);
arr[idx]=temp;
return (right || left) ? 1 : 0;
}

bool canReach(vector<int>& arr, int start) {
return solve(arr, start)==1 ? true : false;
}
};``````