add: 220522 [cpp]

cpp/2205/220522.cpp

@@ -0,0 +1,49 @@
+#include <string>
+#include <iostream>
+
+/**
+ * 647. Palindromic Substrings
+ * Given a string s, return the number of palindromic substrings in it.
+ * A string is a palindrome when it reads the same backward as forward.
+ * A substring is a contiguous sequence of characters within the string.
+ */
+
+class Solution {
+private:
+	int isPalindromeS[1002][1002]{{}};
+
+	const char* str = nullptr;
+
+	int isPalindrome(int L, int R) {
+		if (L > R) return -1;
+		if (isPalindromeS[L][R]) return isPalindromeS[L][R];
+		switch (R - L) {
+			case 0:
+				return isPalindromeS[L][R] = 1;
+			case 1:
+				return isPalindromeS[L][R] = (str[L] == str[R] ? 1 : -1);
+			default:
+				return isPalindromeS[L][R] = (str[L] == str[R] ? isPalindrome(L + 1, R - 1) : -1);
+		}
+	}
+
+public:
+	int countSubstrings(const std::string& s) {
+		this->str = s.c_str();
+		const int len = s.length();
+
+		int ans = 0;
+		for (int i = 0; i < len; ++i) {
+			for (int L = 0; L + i < len; ++L) {
+				ans += isPalindrome(L, L + i) > 0 ? 1 : 0;
+			}
+		}
+		return ans;
+	}
+};
+
+int main() {
+	auto s = new Solution;
+	std::cout << s->countSubstrings("abc");
+	return 0;
+}

cpp/2205/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2205)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2205 220522-CN.cpp)
+ADD_EXECUTABLE(2205 220522.cpp)