<p>Given a string <code>s</code>, partition <code>s</code> such that every <span data-keyword="substring-nonempty">substring</span> of the partition is a <span data-keyword="palindrome-string">palindrome</span>.</p>

<p>Return <em>the <strong>minimum</strong> cuts needed for a palindrome partitioning of</em> <code>s</code>.</p>

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

<pre>
<strong>Input:</strong> s = &quot;aab&quot;
<strong>Output:</strong> 1
<strong>Explanation:</strong> The palindrome partitioning [&quot;aa&quot;,&quot;b&quot;] could be produced using 1 cut.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;a&quot;
<strong>Output:</strong> 0
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;ab&quot;
<strong>Output:</strong> 1
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 2000</code></li>
	<li><code>s</code> consists of lowercase English letters only.</li>
</ul>

class Solution {
public:
    bool isPalindrome(string s, int start, int end){
        while(start<end){
            if(s[start++] != s[end--])
                return false;
        }
        return true;
    }

    int helper(string &s, int i, int n, vector<int> &dp){
        if(i == n)
            return 0;
        if(dp[i] != -1)
            return dp[i];

        int minCost = INT_MAX;
        for(int j=i; j<n; j++){
            if(isPalindrome(s, i, j)){
                int cost = helper(s, j+1, n, dp) + 1;
                minCost = min(minCost, cost);
            }
        }
        return dp[i] = minCost;
    }

    // int minCut(string s) {
    //     int n = s.size();
    //     vector<int> dp(n, -1);
    //     return helper(s, 0, n, dp) - 1;
    // }

    int minCut(string s) {
        int n = s.size();
        vector<int> cut(n+1, 0);  // number of cuts for the first k characters
        for (int i = 0; i <= n; i++)
            cut[i] = i-1;
        for (int i = 0; i < n; i++) {
            for (int j = 0; i-j >= 0 && i+j < n && s[i-j]==s[i+j] ; j++) // odd length palindrome
                cut[i+j+1] = min(cut[i+j+1],1+cut[i-j]);

            for (int j = 1; i-j+1 >= 0 && i+j < n && s[i-j+1] == s[i+j]; j++) // even length palindrome
                cut[i+j+1] = min(cut[i+j+1],1+cut[i-j+1]);
        }
        return cut[n];
    }
};
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