20241210 finished.

src/problem/mod.rs

@@ -360,3 +360,5 @@ mod p688_knight_probability_in_chessboard;
 mod p782_transform_to_chessboard;
 
 mod p1812_determine_color_of_a_chessboard_square;
+
+mod p935_knight_dialer;

src/problem/p935_knight_dialer.rs

@@ -0,0 +1,71 @@
+/**
+ * [935] Knight Dialer
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+const MOD: i32 = 1_000_000_007;
+
+impl Solution {
+    pub fn knight_dialer(n: i32) -> i32 {
+        let n = n as usize;
+
+        let chessboard = vec![
+            // 0
+            vec![4, 6],
+            // 1
+            vec![6, 8],
+            // 2
+            vec![7, 9],
+            // 3
+            vec![4, 8],
+            // 4
+            vec![0, 3, 9],
+            // 5
+            vec![],
+            // 6
+            vec![0, 1, 7],
+            // 7
+            vec![2, 6],
+            // 8
+            vec![1, 3],
+            // 9
+            vec![2, 4],
+        ];
+
+        let mut dp = vec![vec![0; 10], vec![1; 10]];
+
+        for i in 2..=n {
+            (0..10).for_each(|j| dp[i % 2][j] = 0);
+
+            for j in 0..10 {
+                for &next in chessboard[j].iter() {
+                    dp[i % 2][next] = (dp[i % 2][next] + dp[(i - 1) % 2][j]) % MOD;
+                }
+            }
+        }
+
+        let mut result = 0;
+
+        for &i in dp[n % 2].iter() {
+            result = (result + i) % MOD;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_935() {
+        assert_eq!(10, Solution::knight_dialer(1));
+        assert_eq!(20, Solution::knight_dialer(2));
+        assert_eq!(136_006_598, Solution::knight_dialer(3131));
+    }
+}