Number of Distinct Roll Sequences LeetCode solution in Rust

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const DICE_LEN: usize = 7;
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const MOD: usize = 1_000_000_007;
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pub fn gen_next_map() -> [u8; DICE_LEN] {
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  [
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    0b1111110, // 0 -> [1, 2, 3, 4, 5, 6]
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    0b1111100, // 1 -> [2, 3, 4, 5, 6]
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    0b0101010, // 2 -> [1, 3, 5]
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    0b0110110, // 3 -> [1, 2, 4, 5]
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    0b0101010, // 4 -> [1, 3, 5]
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    0b1011110, // 5 -> [1, 2, 3, 4, 6]
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    0b0100010, // 6 -> [1, 5]
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  ]
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}
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impl Solution {
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  pub fn distinct_sequences(n: i32) -> i32 {
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    let n = n as usize - 1;
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    let next_map = gen_next_map();
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    let mut dp = [[usize::MIN; DICE_LEN]; DICE_LEN];
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    for j in 1..DICE_LEN {
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      dp[usize::MIN][j] = 1;
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    }
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    for _ in 0..n {
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      let mut dp_next = [[usize::MIN; DICE_LEN]; DICE_LEN];
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      for prev in 0..DICE_LEN {
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        for i in 0..DICE_LEN {
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          let flags = next_map[i] & !(1 << prev);
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          for j in 0..DICE_LEN {
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            if (flags >> j) & 1 < 1 {
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              continue;
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            }
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            dp_next[i][j] += dp[prev][i];
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          }
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        }
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      }
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      for i in 0..DICE_LEN {
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        for j in 0..DICE_LEN {
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          dp_next[i][j] %= MOD;
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        }
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      }
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      dp = dp_next;
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    }
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    let ret = dp
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      .into_iter()
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      .map(|v| v.into_iter().sum::<usize>() % MOD)
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      .sum::<usize>()
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      % MOD;
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    ret as i32
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  }
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}