palindromic substrings solution

Author: hyer0705

palindromic-substrings/hyer0705.ts

@@ -0,0 +1,34 @@
+function countSubstrings(s: string): number {
+  const sLen = s.length;
+
+  const dp: boolean[][] = Array.from({ length: sLen }, () => Array(sLen).fill(false));
+
+  // 길이가 1
+  for (let i = 0; i < sLen; i++) {
+    dp[i][i] = true;
+  }
+
+  // 길이가 2
+  for (let i = 0; i < sLen - 1; i++) {
+    dp[i][i + 1] = s[i] === s[i + 1];
+  }
+
+  // 길이가 3이상
+  for (let len = 3; len <= sLen; len++) {
+    for (let i = 0; i < sLen - len + 1; i++) {
+      const j = i + len - 1;
+      if (s[i] === s[j] && dp[i + 1][j - 1]) {
+        dp[i][j] = true;
+      }
+    }
+  }
+
+  let count = 0;
+  for (let i = 0; i < dp.length; i++) {
+    for (let j = 0; j < dp[i].length; j++) {
+      if (dp[i][j]) count++;
+    }
+  }
+
+  return count;
+}