day3: (2) dp/11726, dp/11727

dp/타일링_2곱하기n.java

@@ -0,0 +1,35 @@
+package test.boj.dp;
+
+import org.junit.*;
+
+import java.util.Scanner;
+
+public class 타일링_2곱하기n {
+
+    @Test
+    public void test() {
+        System.out.println(solution(1000));
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        System.out.println(solution(sc.nextInt()));
+    }
+
+    // n:    0 1 2 3 4 5 6  7  8  9 ....
+    // F(n): 1 1 2 3 5 8 13 21 34 55 .....
+    private static int solution(int n) {
+        return f(n);
+    }
+
+    private static int f(int n) {
+        int[] fibo = new int[n + 1];
+        fibo[0] = fibo[1] = 1;
+
+        for (int i = 2; i <= n; i++) {
+            // !!! overflow -> % 10007
+            fibo[i] = (fibo[i - 1] + fibo[i -  2]) % 10007;
+        }
+        return fibo[n];
+    }
+}

dp/타일링_2곱하기n_2.java

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+package test.boj.dp;
+
+import org.junit.*;
+
+import java.util.Scanner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+// refer images/타일링_2곱하기n_2.png
+public class 타일링_2곱하기n_2 {
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        System.out.println(solution(sc.nextInt()));
+    }
+
+    @Test
+    public void test() {
+        System.out.println(solution(1));
+        assertThat(solution(2))
+                .isEqualTo(3);
+
+        assertThat(solution(3))
+                .isEqualTo(5);
+
+        assertThat(solution(4))
+                .isEqualTo(11);
+
+        assertThat(solution(1000))
+                .isEqualTo(7326);
+    }
+
+    private static int solution(int n) {
+        int[] dp = new int[n + 2];
+        dp[1] = 1;
+        dp[2] = 3;
+
+        for (int i = 3; i <= n; i++) {
+            dp[i] = (dp[i - 1] + (dp[i - 2] * 2)) % 10_007;
+        }
+        return dp[n];
+    }
+}