<p>There is a strange printer with the following two special properties:</p>

<ul>
	<li>The printer can only print a sequence of <strong>the same character</strong> each time.</li>
	<li>At each turn, the printer can print new characters starting from and ending at any place and will cover the original existing characters.</li>
</ul>

<p>Given a string <code>s</code>, return <em>the minimum number of turns the printer needed to print it</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;aaabbb&quot;
<strong>Output:</strong> 2
<strong>Explanation:</strong> Print &quot;aaa&quot; first and then print &quot;bbb&quot;.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;aba&quot;
<strong>Output:</strong> 2
<strong>Explanation:</strong> Print &quot;aaa&quot; first and then print &quot;b&quot; from the second place of the string, which will cover the existing character &#39;a&#39;.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 100</code></li>
	<li><code>s</code> consists of lowercase English letters.</li>
</ul>

class Solution {
public:
    int solve(string s, int start, int end, vector<vector<int>>& dp) {
        if (start > end)
            return 0;
        if (start == end)
            return 1;
        if (dp[start][end] != -1) {
            return dp[start][end];
        }
        int ans = solve(s, start, end - 1, dp) + 1;
        for (int i = start; i < end; i++) {
            if (s[i] == s[end]) {
                ans = min(ans, solve(s, start, i, dp) +
                                   solve(s, i + 1, end - 1, dp));
            }
        }

        return dp[start][end] = ans;
    }

    int strangePrinter(string s) {
        string uniqueChars;
        int i = 0;
        while (i < s.length()) {
            char currentChar = s[i];
            uniqueChars += currentChar;
            while (i < s.length() && s[i] == currentChar) {
                i++;
            }
        }
        s=uniqueChars;
        vector<vector<int>> dp(s.size() + 1, vector<int>(s.size() + 1, -1));
        return solve(s, 0, s.size() - 1, dp);
    }
};
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