26266. 비즈네르 암호 해독 - 문자열

baekjoon/cpp/c++/26266.cpp

@@ -0,0 +1,72 @@
+#include <bits/stdc++.h>
+
+std::string s1, s2;
+const int MOD = 26;
+
+// i in [0, 25]
+char itoc(int i)
+{
+    return 'A' + i - 1;
+}
+
+int ctoi(char c)
+{
+    return (int)(c - 'A');
+}
+
+void getinput()
+{
+    std::cin >> s1 >> s2;
+}
+
+std::string solve()
+{
+    auto len = s1.length();
+
+    std::vector<int> v;
+    for (int i = 0; i < len; i++)
+    {
+        v.push_back((ctoi(s2[i]) - ctoi(s1[i]) + MOD) % MOD);
+    }
+
+    // for (auto &vv : v)
+    //     std::cout << vv << ' ';
+    // std::cout << '\n';
+
+    std::string ans;
+    for (int i = 1; i <= len; i++)
+    {
+        if (len % i == 0)
+        {
+            bool is_ans = true;
+            for (int j = i; j < len; j++)
+            {
+                if (v[j] != v[j % i])
+                {
+                    is_ans = false;
+                    break;
+                }
+            }
+            if (is_ans)
+            {
+                for (int j = 0; j < i; j++)
+                {
+                    auto mod = v[j] ? v[j] : 26;
+                    ans.push_back(itoc(mod));
+                }
+                return ans;
+            }
+        }
+    }
+
+    exit(-1);
+}
+
+int main()
+{
+    std::ios::sync_with_stdio(false);
+    std::cin.tie(0);
+
+    getinput();
+    std::cout << solve() << '\n';
+}