<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 recur(string s, int idx, int x, int y) {
        if (idx >= s.length())
            return 0;
        int max1 = 0;
        if (idx + 1 < s.length()) {
            if (s[idx] == 'a' && s[idx + 1] == 'b') {
                max1 = max(max1, x + recur(s, idx + 2, x, y));
            } else if (s[idx] == 'b' && s[idx + 1] == 'a') {
                max1 = max(max1, y + recur(s, idx + 2, x, y));
            }
            // else
        }
        max1 = max(max1, recur(s, idx + 1, x, y));
        ;
        return max1;
    }
    int maximumGain(string s, int x, int y) {

        stack<int> st;

        st.push(0);
        int i = 1;
        int sum = 0;
        while (i < s.length()) {
            if (!st.empty()) {
                if (x > y) {
                    if (s[i] == 'b' && s[st.top()] == 'a') {
                        st.pop();
                        sum += x;
                    } else {
                        st.push(i);
                    }

                } else {
                    if (s[i] == 'a' && s[st.top()] == 'b') {
                        st.pop();
                        sum += y;
                    } else {
                        st.push(i);
                    }
                }

            } else
                st.push(i);
            // if(s[i]=='a' )

            i++;
        }
        string rem = "";
        while (!st.empty()) {
            rem += s[st.top()];
            st.pop();
        }
        reverse(rem.begin(), rem.end());
        i = 0;
        while (i < rem.length()) {

            // if(x>y)
            // {
            if (!st.empty()) {
                if (x > y) {
                    if (rem[st.top()] == 'b' && rem[i] == 'a') {
                        sum += y;
                        st.pop();
                        i++;
                        continue;
                    } else {
                        st.push(i);
                        i++;
                        continue;
                    }
                } else {

                    // }
                    // else
                    // {
                    if (rem[st.top()] == 'a' && rem[i] == 'b') {
                        sum += x;
                        st.pop();
                    } else
                        st.push(i);
                }
            } else
                st.push(i);
            i++;
            // }
        }
        return sum;
    }
};
38521