Create minimum-insertion-steps-to-make-a-string-palindrome.cpp

Author: kamyu104

C++/minimum-insertion-steps-to-make-a-string-palindrome.cpp

@@ -0,0 +1,27 @@
+// Time:  O(n^2)
+// Space: O(n)
+
+class Solution {
+public:
+    int minInsertions(string s) {
+        const string reversed_s(s.crbegin(), s.crend());
+        return s.length() - longestCommonSubsequence(s, reversed_s);
+    }
+
+private:
+    int longestCommonSubsequence(const string& text1, const string& text2) {
+        if (text1.length() < text2.length()) {
+            return longestCommonSubsequence(text2, text1);
+        }
+        vector<vector<int>> dp(2, vector<int>(text2.length() + 1));
+        for (int i = 1; i <= text1.length(); ++i) {
+            for (int j = 1; j <= text2.length(); ++j) {
+                dp[i % 2][j] = (text1[i - 1] == text2[j - 1])
+                               ? dp[(i - 1) % 2][j - 1] + 1
+                               : max(dp[(i - 1) % 2][j], dp[i % 2][j - 1]);
+                               
+            }
+        }
+        return dp[text1.length() % 2][text2.length()];
+    }
+};