20250505 finished.

src/problem/mod.rs

@@ -634,3 +634,5 @@ mod p838_push_dominoes;
 mod p1007_minimum_domino_rotations_for_equal_row;
 
 mod p1128_number_of_equivalent_domino_pairs;
+
+mod p790_domino_and_tromino_tiling;

src/problem/p790_domino_and_tromino_tiling.rs

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