DataStructures/PallindromeStrings.java at master · Poorvaa24/DataStructures · GitHub

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package poorvatutorial1;

public class PallindromeStrings {

	static int PallindromeCount(char str[], int n)
	{
		int arr[][] = new int[n][n];

		boolean A[][] = new boolean[n][n];

		for (int i= 0; i< n; i++)
			A[i][i] = true;

		for (int i=0; i<n-1; i++)
		{
			if (str[i] == str[i+1])
			{
				A[i][i+1] = true;
				arr[i][i+1] = 1 ;
			}
		}

		for (int gap=2 ; gap<n; gap++)
		{

			for (int i=0; i<n-gap; i++)
			{

				int j = gap + i;

				if (str[i] == str[j] && A[i+1][j-1] )
					A[i][j] = true;

				if (A[i][j] == true)
					arr[i][j] = arr[i][j-1] + arr[i+1][j] + 1 - arr[i+1][j-1];
				else
					arr[i][j] = arr[i][j-1] + arr[i+1][j] - arr[i+1][j-1];
			}
		}

		return arr[0][n-1];
	}


	public static void main(String[] args) {

		String str = "madam";
		System.out.println(PallindromeCount(str.toCharArray(), str.length()));

	}

}