5 - Longest Palindromic Substring

 JAVA

• class Solution {
      public String longestPalindrome(String s) {
          int n = s.length();
          boolean[][] f = new boolean[n][n];
          for (var g : f) {
              Arrays.fill(g, true);
          }
          int k = 0, mx = 1;
          for (int i = n - 2; i >= 0; --i) {
              for (int j = i + 1; j < n; ++j) {
                  f[i][j] = false;
                  if (s.charAt(i) == s.charAt(j)) {
                      f[i][j] = f[i + 1][j - 1];
                      if (f[i][j] && mx < j - i + 1) {
                          mx = j - i + 1;
                          k = i;
                      }
                  }
              }
          }
          return s.substring(k, k + mx);
      }
  }

C++

• class Solution {
  public:
      string longestPalindrome(string s) {
          int n = s.size();
          vector<vector<bool>> f(n, vector<bool>(n, true));
          int k = 0, mx = 1;
          for (int i = n - 2; ~i; --i) {
              for (int j = i + 1; j < n; ++j) {
                  f[i][j] = false;
                  if (s[i] == s[j]) {
                      f[i][j] = f[i + 1][j - 1];
                      if (f[i][j] && mx < j - i + 1) {
                          mx = j - i + 1;
                          k = i;
                      }
                  }
              }
          }
          return s.substr(k, mx);
      }
  };