Leetcode Problem 1216. Valid Palindrome III

1216. Valid Palindrome III

Leetcode Solutions

Approach: Top-Down Dynamic Programming (D)

  1. Create a 2D memoization array memo with dimensions n x n, where n is the length of the string s.
  2. Define a recursive function helper(i, j) that takes two pointers i and j as arguments, representing the current substring s[i...j].
  3. If i >= j, return 0, as a string with length 0 or 1 is already a palindrome.
  4. If memo[i][j] is not -1, return its value as the result has already been computed.
  5. If s[i] equals s[j], set memo[i][j] to the result of helper(i + 1, j - 1).
  6. If s[i] does not equal s[j], set memo[i][j] to the minimum of helper(i + 1, j) and helper(i, j - 1) plus 1.
  7. Return memo[i][j] as the result for the current subproblem.
  8. Call helper(0, n - 1) and check if the result is less than or equal to k. If it is, return true; otherwise, return false.
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Approach: Bottom-Up Dynamic Programming (D)

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