Find the Substring With Maximum Cost
<p>You are given a string <code>s</code>, a string <code>chars</code> of <strong>distinct</strong> characters and an integer array <code>vals</code> of the same length as <code>chars</code>.</p>

<p>The <strong>cost of the substring </strong>is the sum of the values of each character in the substring. The cost of an empty string is considered <code>0</code>.</p>

<p>The <strong>value of the character </strong>is defined in the following way:</p>

<ul>
	<li>If the character is not in the string <code>chars</code>, then its value is its corresponding position <strong>(1-indexed)</strong> in the alphabet.

    <ul>
    	<li>For example, the value of <code>&#39;a&#39;</code> is <code>1</code>, the value of <code>&#39;b&#39;</code> is <code>2</code>, and so on. The value of <code>&#39;z&#39;</code> is <code>26</code>.</li>
    </ul>
    </li>
    <li>Otherwise, assuming <code>i</code> is the index where the character occurs in the string <code>chars</code>, then its value is <code>vals[i]</code>.</li>

</ul>

<p>Return <em>the maximum cost among all substrings of the string</em> <code>s</code>.</p>

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

<pre>
<strong>Input:</strong> s = &quot;adaa&quot;, chars = &quot;d&quot;, vals = [-1000]
<strong>Output:</strong> 2
<strong>Explanation:</strong> The value of the characters &quot;a&quot; and &quot;d&quot; is 1 and -1000 respectively.
The substring with the maximum cost is &quot;aa&quot; and its cost is 1 + 1 = 2.
It can be proven that 2 is the maximum cost.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;abc&quot;, chars = &quot;abc&quot;, vals = [-1,-1,-1]
<strong>Output:</strong> 0
<strong>Explanation:</strong> The value of the characters &quot;a&quot;, &quot;b&quot; and &quot;c&quot; is -1, -1, and -1 respectively.
The substring with the maximum cost is the empty substring &quot;&quot; and its cost is 0.
It can be proven that 0 is the maximum cost.
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
	<li><code>s</code> consist of lowercase English letters.</li>
	<li><code>1 &lt;= chars.length &lt;= 26</code></li>
	<li><code>chars</code> consist of <strong>distinct</strong> lowercase English letters.</li>
	<li><code>vals.length == chars.length</code></li>
	<li><code>-1000 &lt;= vals[i] &lt;= 1000</code></li>
</ul>
Array; Hash Table; String; Dynamic Programming
class Solution {
public:
    int maximumCostSubstring(string s, string chars, vector<int>& vals) {
        vector<int> d(26);
        iota(d.begin(), d.end(), 1);
        int m = chars.size();
        for (int i = 0; i < m; ++i) {
            d[chars[i] - 'a'] = vals[i];
        }
        int ans = 0, tot = 0, mi = 0;
        for (char& c : s) {
            int v = d[c - 'a'];
            tot += v;
            ans = max(ans, tot - mi);
            mi = min(mi, tot);
        }
        return ans;
    }
};