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Java-based LeetCode algorithm problem solutions, regularly updated

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package g2301_2400.s2396_strictly_palindromic_number;

// #Medium #Math #Two_Pointers #Brainteaser #2022_09_14_Time_0_ms_(100.00%)_Space_40.6_MB_(75.27%)

/**
 * 2396 - Strictly Palindromic Number\.
 *
 * Medium
 *
 * An integer `n` is **strictly palindromic** if, for **every** base `b` between `2` and `n - 2` ( **inclusive** ), the string representation of the integer `n` in base `b` is **palindromic**.
 *
 * Given an integer `n`, return `true` _if_ `n` _is **strictly palindromic** and_ `false` _otherwise_.
 *
 * A string is **palindromic** if it reads the same forward and backward.
 *
 * **Example 1:**
 *
 * **Input:** n = 9
 *
 * **Output:** false
 *
 * **Explanation:** In base 2: 9 = 1001 (base 2), which is palindromic.
 *
 * In base 3: 9 = 100 (base 3), which is not palindromic.
 *
 * Therefore, 9 is not strictly palindromic so we return false.
 *
 * Note that in bases 4, 5, 6, and 7, n = 9 is also not palindromic. 
 *
 * **Example 2:**
 *
 * **Input:** n = 4
 *
 * **Output:** false
 *
 * **Explanation:** We only consider base 2: 4 = 100 (base 2), which is not palindromic.
 *
 * Therefore, we return false. 
 *
 * **Constraints:**
 *
 * *   4 <= n <= 10⁵
**/
public class Solution {
    public boolean isStrictlyPalindromic(int n) {
        for (int i = 2; i <= n - 2; i++) {
            String num = Integer.toString(i);
            String s = baseConversion(num, 10, i);
            if (!checkPalindrome(s)) {
                return false;
            }
        }
        return true;
    }

    private String baseConversion(String number, int sBase, int dBase) {
        // Parse the number with source radix
        // and return in specified radix(base)
        return Integer.toString(Integer.parseInt(number, sBase), dBase);
    }

    private boolean checkPalindrome(String s) {
        int start = 0;
        int end = s.length() - 1;
        while (start <= end) {
            if (s.charAt(start) != s.charAt(end)) {
                return false;
            }
            start++;
            end--;
        }
        return true;
    }
}