feat: 647. Palindromic Substrings

Author: gwbaik9717

palindromic-substrings/gwbaik9717.js

@@ -0,0 +1,46 @@
+// Time complexity: O(n^2)
+// Space complexity: O(n^2)
+
+/**
+ * @param {string} s
+ * @return {number}
+ */
+var countSubstrings = function (s) {
+  const n = s.length;
+  const dp = Array.from({ length: n }, () =>
+    Array.from({ length: n }, () => false)
+  );
+
+  for (let end = 0; end < n; end++) {
+    for (let start = end; start >= 0; start--) {
+      if (start === end) {
+        dp[start][end] = true;
+        continue;
+      }
+
+      if (start + 1 === end) {
+        if (s[start] === s[end]) {
+          dp[start][end] = true;
+        }
+        continue;
+      }
+
+      if (s[start] === s[end] && dp[start + 1][end - 1]) {
+        dp[start][end] = true;
+        continue;
+      }
+    }
+  }
+
+  let answer = 0;
+
+  for (let i = 0; i < n; i++) {
+    for (let j = 0; j < n; j++) {
+      if (dp[i][j]) {
+        answer++;
+      }
+    }
+  }
+
+  return answer;
+};