Merge pull request #597 from AlgorithmWithGod/LiiNi-coder

[20250802] BOJ / G5 / 1학년 / 이인희

Author: ShinHeeEul

LiiNi-coder/202508/02 BOJ 1학년.md

@@ -0,0 +1,45 @@
+```java
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class Main {
+
+    static int N;
+    static int[] A;
+    static long[][] dp; // [index][sum], sum은 0이상 20미만
+    static long dfs(int idx, int result) {
+        if (result < 0 || result > 20) return 0;
+        if (idx == 0) {
+            // idx==0이면 a = a 인것 1개의 경우의수 아니면 a = b형태라 0의 경우의수
+            return (result == A[0])? 1 : 0;
+        }
+        if (dp[idx][result] != -1) return dp[idx][result];
+
+        long count = 0; // 경우의수
+        count += dfs(idx - 1, result + A[idx]);
+        count += dfs(idx - 1, result - A[idx]);
+        dp[idx][result] = count;
+        return count;
+    }
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        N = Integer.parseInt(br.readLine());
+        A = new int[N];
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) {
+            A[i] = Integer.parseInt(st.nextToken());
+        }
+
+        dp = new long[N][21]; // 인덱스: 0~N-1, sum: 0~20
+        for (int i = 0; i < N; i++) {
+            for (int j = 0; j <= 20; j++) {
+                dp[i][j] = -1;
+            }
+        }
+
+        System.out.println(dfs(N - 2, A[N - 1]));
+    }
+}
+```