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Create Longest Palindromic Subsequence #36

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Create Longest Palindromic Subsequence #36

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51 changes: 51 additions & 0 deletions src/main/java/com/rampatra/strings/Longest Palindromic Subsequence
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Original file line number Diff line number Diff line change
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import java.util.*;
import java.io.*;

class home{
public static void main(String args[]){
Scanner sc= new Scanner (System.in);
int t=sc.nextInt();
while(t-->0){
String s=sc.next();
Solution obj = new Solution();
System.out.println(obj.longestPalinSubseq(s);
}
}
}

class Solution
{
public int longestPalinSubseq(String A)
{

int n = A.length();

StringBuilder st = new StringBuilder();
st.append(A);
st.reverse();

String B = st.toString();

// a palindrome reads the same from front and reverse.
// hence, the longest palindromic subsequence is
// basically the longest common subsequence in
// A and reverse(A)
int[][] dp = new int[n + 1][n + 1];
for (int i = 0; i <= n; ++i)
{
for (int j = 0; j <= n; ++j)
{
if (i == 0 || j == 0)
dp[i][j] = 0;
else
{
if (A.charAt(i - 1) == B.charAt(j - 1))
dp[i][j] = 1 + dp[i - 1][j - 1];
else
dp[i][j] = Math.max (dp[i - 1][j], dp[i][j - 1]);
}
}
}
return dp[n][n];
}
}