Number of Ways to Stay in the Same Place After Some Steps LeetCode solution in Java

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class Solution {
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  HashMap<String, Long> map = new HashMap();
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  public int numWays(int steps, int arrLen) {
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    return (int) (ways(steps, arrLen, 0) % ((Math.pow(10, 9)) + 7));
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  }
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  public long ways(int steps, int arrLen, int index) {
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    String curr = index + "->" + steps;
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    if (index == 0 && steps == 0) {
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      return 1;
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    } else if (index < 0 || (index >= arrLen) || steps == 0) {
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      return 0;
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    }
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    if (map.containsKey(curr)) {
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      return map.get(curr);
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    }
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    long stay = ways(steps - 1, arrLen, index);
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    long right = ways(steps - 1, arrLen, index + 1);
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    long left = ways(steps - 1, arrLen, index - 1);
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    map.put(curr, (stay + right + left) % 1000000007);
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    return (right + left + stay) % 1000000007;
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  }
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}