Solution (leetcode-in-java 1.21 API)

java.lang.Object
- g1201_1300.s1269_number_of_ways_to_stay_in_the_same_place_after_some_steps.Solution

```
public class Solution
extends Object
```
1269 - Number of Ways to Stay in the Same Place After Some Steps.
Hard

You have a pointer at index 0 in an array of size arrLen. At each step, you can move 1 position to the left, 1 position to the right in the array, or stay in the same place (The pointer should not be placed outside the array at any time).

Given two integers steps and arrLen, return the number of ways such that your pointer still at index 0 after exactly steps steps. Since the answer may be too large, return it modulo 10⁹ + 7.

Example 1:

Input: steps = 3, arrLen = 2

Output: 4

Explanation: There are 4 differents ways to stay at index 0 after 3 steps.

Right, Left, Stay

Stay, Right, Left

Right, Stay, Left

Stay, Stay, Stay

Example 2:

Input: steps = 2, arrLen = 4

Output: 2

Explanation: There are 2 differents ways to stay at index 0 after 2 steps

Right, Left

Stay, Stay

Example 3:

Input: steps = 4, arrLen = 2

Output: 8

Constraints:
- 1 <= steps <= 500
- 1 <= arrLen <= 10⁶

- Constructor Summary
  
  Constructors
  Constructor Description
  
  Solution()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  int numWays(int steps, int arrLen)
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- Solution
```
public Solution()
```

Method Detail

numWays

public int numWays(int steps,
                   int arrLen)