First Day Where You Have Been in All the Rooms LeetCode solution in Java

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class Solution {
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  public int firstDayBeenInAllRooms(int[] nextVisit) {
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    int rooms = nextVisit.length;
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    long dp[] = new long[rooms];
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    int mod = (int) (1e9) + 7;
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    for (int i = 1; i < rooms; i++) {
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      if (nextVisit[i - 1] == i - 1) dp[i] = dp[i - 1] + 2;
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      else dp[i] = (dp[i - 1] + dp[i - 1] - dp[nextVisit[i - 1]] + 2 + mod) % mod;
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    }
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    return (int) dp[rooms - 1];
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  }
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}