20250505 finished.
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@ -634,3 +634,5 @@ mod p838_push_dominoes;
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mod p1007_minimum_domino_rotations_for_equal_row;
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mod p1128_number_of_equivalent_domino_pairs;
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mod p790_domino_and_tromino_tiling;
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50
src/problem/p790_domino_and_tromino_tiling.rs
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50
src/problem/p790_domino_and_tromino_tiling.rs
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@ -0,0 +1,50 @@
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/**
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* [790] Domino and Tromino Tiling
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*/
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pub struct Solution {}
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// submission codes start here
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const MOD: i32 = 1_000_000_007;
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impl Solution {
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pub fn num_tilings(n: i32) -> i32 {
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let n = n as usize;
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let mut dp = vec![0; n + 1];
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dp[0] = 1;
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let mut prefix = 0;
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// dp的最后必须是平整的
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// dp[n] = dp[n - 1] + dp[n - 2] + for i in 0..=n-3 Sum(dp[i] * 2)
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for i in 1..=n {
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dp[i] = dp[i - 1] % MOD;
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if i >= 2 {
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dp[i] = (dp[i] + dp[i - 2]) % MOD;
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}
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if i >= 3 {
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prefix = (prefix + dp[i - 3] * 2 % MOD) % MOD;
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dp[i] = (dp[i] + prefix) % MOD;
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}
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}
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dp[n]
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}
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}
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// submission codes end
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_790() {
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assert_eq!(1, Solution::num_tilings(1));
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assert_eq!(2, Solution::num_tilings(2));
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assert_eq!(5, Solution::num_tilings(3));
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assert_eq!(11, Solution::num_tilings(4));
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assert_eq!(312342182, Solution::num_tilings(30));
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}
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}
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