Number of People Aware of a Secret LeetCode solution in Java

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class Solution {
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  public int peopleAwareOfSecret(int n, int delay, int forget) {
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    long mod = 1000000007L;
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    long[] shares = new long[n + 1];
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    long[] forgets = new long[n + 1];
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    if (delay < n) {
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      shares[delay + 1] = 1;
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    }
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    if (forget < n) {
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      forgets[forget + 1] = 1;
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    }
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    long shareToday = 0;
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    long peopleKnow = 1;
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    for (int i = delay; i <= n; i++) {
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      shareToday += shares[i] % mod;
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      shareToday -= forgets[i] % mod;
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      peopleKnow -= forgets[i] % mod;
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      peopleKnow += shareToday % mod;
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      if (i + delay < n + 1) {
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        shares[i + delay] += shareToday % mod;
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      }
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      if (i + forget < n + 1) {
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        forgets[i + forget] += shareToday % mod;
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      }
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    }
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    return (int) (peopleKnow % mod);
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  }
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}