<p>You are given a string <code>s</code> and two integers <code>x</code> and <code>y</code>. You can perform two types of operations any number of times.</p>

<ul>
	<li>Remove substring <code>&quot;ab&quot;</code> and gain <code>x</code> points.

	<ul>
		<li>For example, when removing <code>&quot;ab&quot;</code> from <code>&quot;c<u>ab</u>xbae&quot;</code> it becomes <code>&quot;cxbae&quot;</code>.</li>
	</ul>
	</li>
	<li>Remove substring <code>&quot;ba&quot;</code> and gain <code>y</code> points.
	<ul>
		<li>For example, when removing <code>&quot;ba&quot;</code> from <code>&quot;cabx<u>ba</u>e&quot;</code> it becomes <code>&quot;cabxe&quot;</code>.</li>
	</ul>
	</li>
</ul>

<p>Return <em>the maximum points you can gain after applying the above operations on</em> <code>s</code>.</p>

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

<pre>
<strong>Input:</strong> s = &quot;cdbcbbaaabab&quot;, x = 4, y = 5
<strong>Output:</strong> 19
<strong>Explanation:</strong>
- Remove the &quot;ba&quot; underlined in &quot;cdbcbbaaa<u>ba</u>b&quot;. Now, s = &quot;cdbcbbaaab&quot; and 5 points are added to the score.
- Remove the &quot;ab&quot; underlined in &quot;cdbcbbaa<u>ab</u>&quot;. Now, s = &quot;cdbcbbaa&quot; and 4 points are added to the score.
- Remove the &quot;ba&quot; underlined in &quot;cdbcb<u>ba</u>a&quot;. Now, s = &quot;cdbcba&quot; and 5 points are added to the score.
- Remove the &quot;ba&quot; underlined in &quot;cdbc<u>ba</u>&quot;. Now, s = &quot;cdbc&quot; and 5 points are added to the score.
Total score = 5 + 4 + 5 + 5 = 19.</pre>

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

<pre>
<strong>Input:</strong> s = &quot;aabbaaxybbaabb&quot;, x = 5, y = 4
<strong>Output:</strong> 20
</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>1 &lt;= x, y &lt;= 10<sup>4</sup></code></li>
	<li><code>s</code> consists of lowercase English letters.</li>
</ul>

class Solution {
public:
    int ret;

    string reverseStringstr(string str) {
        string ret = "";
        int n = str.length();
        for (int i = n - 1; i >= 0; i--) {
            ret += str[i];
        }
        return ret;
    }

    string removeABPattern(string str, int val) {
        stack<char> st;
        int n = str.length();
        for (int i = 0; i < n; i++) {
            if (str[i] == 'b' && !st.empty() && st.top() == 'a') {
                ret += val;
                st.pop();
            }
            else {
                st.push(str[i]);
            }
        }
        string temp = "";
        while (!st.empty()) {
            temp += st.top();
            st.pop();
        }
        temp = reverseStringstr(temp);
        return temp;
    }

    string removeBAPattern(string str, int val) {
        stack<char> st;
        int n = str.length();
        for (int i = 0; i < n; i++) {
            if (str[i] == 'a' && !st.empty() && st.top() == 'b') {
                ret += val;
                st.pop();
            }
            else {
                st.push(str[i]);
            }
        }
        string temp = "";
        while (!st.empty()) {
            temp += st.top();
            st.pop();
        }
        temp = reverseStringstr(temp);
        return temp;
    }

    int maximumGain(string s, int x, int y) {
        ret = 0;
        if (x > y) {
            string temp = removeABPattern(s, x);
            temp = removeBAPattern(temp, y);
        }
        else {
            string temp = removeBAPattern(s, y);
            temp = removeABPattern(temp, x);
        }
        return ret;
    }
};
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