[Week08] BOJ 15989: 1, 2, 3 더하기 4

Author: JAEHEE25

personal/JAEHEE25/BOJ/BOJ15988.java

@@ -0,0 +1,27 @@
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+class Main {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        //dp
+        long[] dp = new long[1000001];
+        dp[1] = 1;
+        dp[2] = 2;
+        dp[3] = 4;
+        for (int i = 4; i <= 1000000; i++) {
+            dp[i] = (dp[i - 3] + dp[i - 2] + dp[i - 1]) % 1_000_000_009;
+        }
+
+        //정답 출력
+        StringBuilder answer = new StringBuilder();
+        int T = Integer.parseInt(br.readLine());
+        for (int i = 0; i < T; i++) {
+            int t = Integer.parseInt(br.readLine());
+            answer.append(dp[t] % 1_000_000_009).append("\n");
+        }
+        System.out.println(answer);
+    }
+}

weekly/week08/BOJ_15989_1,2,3더하기4/JAEHEE25.java

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+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+class BOJ15989 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        //dp[i][j] = i를 만들 때 마지막 숫자가 j이고, 오름차순인 방법의 수
+        int[][] dp = new int[10001][4];
+        dp[1][1] = 1; //1
+        dp[2][1] = 1; //1,1
+        dp[2][2] = 1; //2
+        dp[3][1] = 1; //1,1,1
+        dp[3][2] = 1; //1,2
+        dp[3][3] = 1; //3
+        for (int i = 4; i <= 10000; i++) {
+            dp[i][1] = dp[i-1][1];
+            dp[i][2] = dp[i-2][1] + dp[i-2][2];
+            dp[i][3] = dp[i-3][1] + dp[i-3][2] + dp[i-3][3];
+        }
+
+        //정답 출력
+        StringBuilder answer = new StringBuilder();
+        int T = Integer.parseInt(br.readLine());
+        for (int i = 0; i < T; i++) {
+            int t = Integer.parseInt(br.readLine());
+            answer.append(dp[t][1] + dp[t][2] + dp[t][3]).append("\n");
+        }
+        System.out.println(answer);
+    }
+}