[20250205] BOJ / P4 / 시저 암호 / 신희을

Author: ShinHeeEul

ShinHeeEul/202502/05 BOJ P4 시저 암호.md

@@ -0,0 +1,96 @@
+```java
+import java.util.*;
+import java.io.*;
+
+public class Main {
+
+	static int[] failure;
+	public static void main(String[] args) throws IOException {
+		
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		
+		int T = Integer.parseInt(br.readLine());
+
+		StringBuilder sb = new StringBuilder();
+		
+		while(T --> 0) {
+			ArrayList<Integer> list = new ArrayList<>();
+			HashMap<Character, Integer> map = new HashMap<>();
+			
+			char[] A = br.readLine().toCharArray();
+			char[] W = br.readLine().toCharArray();
+			char[] S = br.readLine().toCharArray();
+			int aLength = A.length;
+			for(int i = 0; i < aLength; i++) {
+				map.put(A[i], i);
+			}
+			failure = new int[W.length];
+
+			failureFunction(W);
+			
+			for(int i = 0; i < aLength; i++) {
+				if(i != 0) {
+					for(int j = 0; j < S.length; j++) {
+						S[j] = A[(map.get(S[j]) + 1) % aLength];
+					}
+				}
+				
+				if(kmp(S, W)) {
+					list.add(i == 0 ? i : aLength - i);
+				}
+			}
+			if(list.size() == 0) {
+				sb.append("no solution").append("\n");
+			} else if(list.size() == 1) {
+				sb.append("unique: ").append(list.get(0)).append("\n");
+			} else {
+				Collections.sort(list);
+				sb.append("ambiguous: ");
+				for(int li : list) sb.append(li).append(" ");
+				sb.append("\n");
+			}
+		}
+		System.out.println(sb);
+	}
+	
+	public static void failureFunction(char[] pattern) {
+		
+		int pIdx = 0;
+		
+		for(int i = 1; i < pattern.length; i++) {
+			
+			while(pIdx != 0 && pattern[pIdx] != pattern[i]) 
+				pIdx = failure[pIdx - 1];
+			
+			if(pattern[pIdx] == pattern[i]) {
+				failure[i] = ++pIdx;
+			}
+		}
+	}
+	
+	public static boolean kmp(char[] s, char[] pattern) {
+		int pIdx = 0;
+		int max = 0;
+		// ABCBBABC
+		// ABC
+		// 
+		for(int i = 0; i < s.length; i++) {
+			
+			while(pIdx != 0 && pattern[pIdx] != s[i]) 
+				pIdx = failure[pIdx - 1];
+			
+			if(pattern[pIdx] == s[i]) {
+				if(pIdx == pattern.length - 1) {
+					max++;
+					pIdx = failure[pIdx];
+				} else {
+					pIdx++;
+				}
+			}
+		}
+		
+		return max == 1;
+	}
+
+}
+```