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Java-based LeetCode algorithm problem solutions, regularly updated

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package g0601_0700.s0664_strange_printer;

// #Hard #String #Dynamic_Programming #2022_03_22_Time_24_ms_(76.35%)_Space_42_MB_(87.89%)

/**
 * 664 - Strange Printer\.
 *
 * Hard
 *
 * There is a strange printer with the following two special properties:
 *
 * *   The printer can only print a sequence of **the same character** each time.
 * *   At each turn, the printer can print new characters starting from and ending at any place and will cover the original existing characters.
 *
 * Given a string `s`, return _the minimum number of turns the printer needed to print it_.
 *
 * **Example 1:**
 *
 * **Input:** s = "aaabbb"
 *
 * **Output:** 2
 *
 * **Explanation:** Print "aaa" first and then print "bbb".
 *
 * **Example 2:**
 *
 * **Input:** s = "aba"
 *
 * **Output:** 2
 *
 * **Explanation:** Print "aaa" first and then print "b" from the second place of the string, which will cover the existing character 'a'.
 *
 * **Constraints:**
 *
 * *   `1 <= s.length <= 100`
 * *   `s` consists of lowercase English letters.
**/
public class Solution {
    public int strangePrinter(String s) {
        if (s.length() == 0) {
            return 0;
        }
        int[][] dp = new int[s.length()][s.length()];
        for (int i = s.length() - 1; i >= 0; i--) {
            for (int j = i; j < s.length(); j++) {
                if (i == j) {
                    dp[i][j] = 1;
                } else if (s.charAt(i) == s.charAt(i + 1)) {
                    dp[i][j] = dp[i + 1][j];
                } else {
                    dp[i][j] = dp[i + 1][j] + 1;
                    for (int k = i + 1; k <= j; k++) {
                        if (s.charAt(k) == s.charAt(i)) {
                            dp[i][j] = Math.min(dp[i][j], dp[i + 1][k - 1] + dp[k][j]);
                        }
                    }
                }
            }
        }
        return dp[0][s.length() - 1];
    }
}