Merge pull request #41 from masx200/longest-palindromic-subsequence

longestPalindromeSubseq

Author: masx200

README.md

@@ -49,6 +49,8 @@ Step 2. Add the dependency
 
 <summary>展开查看</summary>
 
+https://leetcode-cn.com/problems/longest-palindromic-subsequence/
+
 https://leetcode.cn/problems/minimum-number-of-operations-to-reinitialize-a-permutation/
 
 https://leetcode.cn/problems/palindromic-substrings/

longest-palindromic-subsequence/index.ts

@@ -0,0 +1,19 @@
+function longestPalindromeSubseq(s: string): number {
+    const n = s.length;
+    const dp: number[][] = new Array(n).fill(0).map(() => new Array(n).fill(0));
+    for (let i = n - 1; i >= 0; i--) {
+        dp[i][i] = 1;
+        const c1 = s[i];
+        for (let j = i + 1; j < n; j++) {
+            const c2 = s[j];
+            if (c1 === c2) {
+                dp[i][j] = dp[i + 1][j - 1] + 2;
+            } else {
+                dp[i][j] = Math.max(dp[i + 1][j], dp[i][j - 1]);
+            }
+        }
+    }
+    return dp[0][n - 1];
+}
+
+export default longestPalindromeSubseq;