[20250223] SWEA / D4 / 동아리실 관리하기 / 이강현

Author: lkhyun

lkhyun/202502/23 SWEA D4 동아리실 관리하기.md

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+```java
+import java.util.*;
+import java.io.*;
+
+public class solution {
+    static final int MOD = 1000000007;
+
+    public static void main(String[] args) throws Exception{
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        int T = Integer.parseInt(br.readLine());
+        for(int t = 1;t<=T; t++){
+            String str = br.readLine();
+            int N = str.length();
+            int[] respBits = new int[N];
+            for (int i = 0; i < N; i++) {
+                respBits[i] = charToInt(str.charAt(i));
+            }
+            List<Integer>[] daySubsets = new List[N];
+            for(int i=0;i<N;i++){
+                daySubsets[i] = new ArrayList<>();
+                for(int mask=1;mask<16;mask++){
+                    if((mask & respBits[i])==0) continue;
+                    if(i==0 && (mask&1)==0) continue;
+                    daySubsets[i].add(mask);
+                }
+            }
+            long[] dpPrev = new long[16];
+            long[] dpCur = new long[16];
+
+            for(int mask : daySubsets[0]){
+                dpPrev[mask] = 1;
+            }
+            for(int day=1; day<N;day++){
+                Arrays.fill(dpCur,0);
+
+                for(int curMask : daySubsets[day]){
+                    long sum = 0;
+                    for(int prevMask : daySubsets[day-1]){
+                        if((curMask&prevMask)!=0){
+                            sum += dpPrev[prevMask];
+                        }
+                    }
+                    dpCur[curMask] = sum % MOD;
+                }
+                dpPrev = Arrays.copyOf(dpCur,16);
+            }
+            long answer = 0;
+            for(int mask : daySubsets[N-1]){
+                answer = (answer + dpPrev[mask]) % MOD;
+            }
+            bw.write("#"+t+" "+answer+"\n");
+        }
+        bw.flush();
+    }
+    public static int charToInt(char c){
+        switch (c){
+            case 'A' : return 1;
+            case 'B' : return 2;
+            case 'C' : return 4;
+            case 'D' : return 8;
+        }
+        return 0;
+    }
+}
+
+```