Dice Roll Simulation LeetCode solution in Java

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class Solution {
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  long[][][] dp;
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  int mod = 1_000_000_007;
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  public int dieSimulator(int n, int[] rollMax) {
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    dp = new long[n + 1][7][16];
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    for (long[][] row : dp) for (long[] col : row) Arrays.fill(col, -1);
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    return (int) helper(n, 0, 0, rollMax, 0);
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  }
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  private long helper(int n, int dice, int prev, int[] rollMax, int runs) {
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    if (n == dice) return 1;
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    if (dp[dice][prev][runs] != -1) return dp[dice][prev][runs];
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    long ans = 0;
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    int[] temp = rollMax;
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    for (int i = 1; i <= 6; i++) {
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      if (prev != 0 && i == prev && rollMax[i - 1] <= runs) continue;
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      if (i == prev) ans = (ans + helper(n, dice + 1, i, rollMax, runs + 1)) % mod;
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      else ans = (ans + helper(n, dice + 1, i, rollMax, 1)) % mod;
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    }
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    dp[dice][prev][runs] = ans;
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    return ans;
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  }
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}