aboutsummaryrefslogtreecommitdiff
path: root/longest_palindromic_subseq.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'longest_palindromic_subseq.cpp')
-rw-r--r--longest_palindromic_subseq.cpp35
1 files changed, 35 insertions, 0 deletions
diff --git a/longest_palindromic_subseq.cpp b/longest_palindromic_subseq.cpp
new file mode 100644
index 0000000..f2a074f
--- /dev/null
+++ b/longest_palindromic_subseq.cpp
@@ -0,0 +1,35 @@
+// 516. Longest Palindromic Subsequence
+#include "leetcode.h"
+
+/*
+ * given string 's', find the longest palindromic susbsequences
+ * of length in 's'. a subsequcnes is a sequence that can be derived
+ * from another sequence by deleting some or no elements without
+ * changing the order of the remaining elements
+ */
+
+class Solution {
+public:
+ int longestPalindromeSubseq(string s) {
+ int n = s.size();
+ vector<int> dp(n, 0);
+ for (int i = n - 1; i >= 0; i--) {
+ vector<int> new_dp(n, 0);
+ new_dp[i] = 1;
+ for (int j = i + 1; j < n; j++) {
+ if (s[i] == s[j])
+ new_dp[j] = 2 + dp[j - 1];
+ else
+ new_dp[j] = max(dp[j], new_dp[j - 1]);
+ }
+ dp = new_dp;
+ }
+ return dp[n - 1];
+ }
+};
+
+int main() {
+ Solution obj;
+ printf("%d\n", obj.longestPalindromeSubseq("bbbab")); // expect: 4
+ printf("%d\n", obj.longestPalindromeSubseq("cbbd")); // expect: 2
+}