<p>You are given a <strong>0-indexed</strong> string <code>s</code>. You are also given a <strong>0-indexed</strong> string <code>queryCharacters</code> of length <code>k</code> and a <strong>0-indexed</strong> array of integer <strong>indices</strong> <code>queryIndices</code> of length <code>k</code>, both of which are used to describe <code>k</code> queries.</p>

<p>The <code>i<sup>th</sup></code> query updates the character in <code>s</code> at index <code>queryIndices[i]</code> to the character <code>queryCharacters[i]</code>.</p>

<p>Return <em>an array</em> <code>lengths</code> <em>of length </em><code>k</code><em> where</em> <code>lengths[i]</code> <em>is the <strong>length</strong> of the <strong>longest substring</strong> of </em><code>s</code><em> consisting of <strong>only one repeating</strong> character <strong>after</strong> the</em> <code>i<sup>th</sup></code> <em>query</em><em> is performed.</em></p>

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

<pre>
<strong>Input:</strong> s = &quot;babacc&quot;, queryCharacters = &quot;bcb&quot;, queryIndices = [1,3,3]
<strong>Output:</strong> [3,3,4]
<strong>Explanation:</strong> 
- 1<sup>st</sup> query updates s = &quot;<u>b<strong>b</strong>b</u>acc&quot;. The longest substring consisting of one repeating character is &quot;bbb&quot; with length 3.
- 2<sup>nd</sup> query updates s = &quot;bbb<u><strong>c</strong>cc</u>&quot;. 
  The longest substring consisting of one repeating character can be &quot;bbb&quot; or &quot;ccc&quot; with length 3.
- 3<sup>rd</sup> query updates s = &quot;<u>bbb<strong>b</strong></u>cc&quot;. The longest substring consisting of one repeating character is &quot;bbbb&quot; with length 4.
Thus, we return [3,3,4].
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;abyzz&quot;, queryCharacters = &quot;aa&quot;, queryIndices = [2,1]
<strong>Output:</strong> [2,3]
<strong>Explanation:</strong>
- 1<sup>st</sup> query updates s = &quot;ab<strong>a</strong><u>zz</u>&quot;. The longest substring consisting of one repeating character is &quot;zz&quot; with length 2.
- 2<sup>nd</sup> query updates s = &quot;<u>a<strong>a</strong>a</u>zz&quot;. The longest substring consisting of one repeating character is &quot;aaa&quot; with length 3.
Thus, we return [2,3].
</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> consists of lowercase English letters.</li>
	<li><code>k == queryCharacters.length == queryIndices.length</code></li>
	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
	<li><code>queryCharacters</code> consists of lowercase English letters.</li>
	<li><code>0 &lt;= queryIndices[i] &lt; s.length</code></li>
</ul>

class Solution {
public:
    struct Node {
        char prefixChar;
        char suffixChar;
        int prefixLen;
        int suffixLen;
        int maxLen;
        int totalLen;
        Node(char c) {
            prefixChar = c;
            suffixChar = c;
            prefixLen = 1;
            suffixLen = 1;
            maxLen = 1;
            totalLen = 1;
        }

        void merge(Node* l, Node* r) {
            maxLen = max(l->maxLen, r->maxLen);
            if(l->suffixChar == r->prefixChar) {
                maxLen = max(maxLen, l->suffixLen+r->prefixLen);
            }
            totalLen = l->totalLen + r->totalLen;

            prefixChar = l->prefixChar;
            suffixChar = r->suffixChar;
            prefixLen = l->prefixLen + (l->prefixLen == l->totalLen && l->suffixChar == r->prefixChar ? r->prefixLen : 0);
            suffixLen = r->suffixLen + (r->suffixLen == r->totalLen && l->suffixChar == r->prefixChar ? l->suffixLen : 0);
        }
    };

    vector<struct Node*> st;

    void buildST(string& s, int idx, int l, int r) {
        st[idx] = new Node(s[l]);
        if(l != r) {
            int m = l + (r-l)/2;
            buildST(s, 2*idx+1, l, m);
            buildST(s, 2*idx+2, m+1, r);
            st[idx]->merge(st[2*idx+1], st[2*idx+2]);
        }
    }

    void update(int idx, int pos, char c, int l, int r) {
        if(l == r) {
            st[idx]->prefixChar = c;
            st[idx]->suffixChar = c;
            return;
        }

        int m = l + (r-l)/2;
        if(pos <= m) {
            update(2*idx+1, pos, c, l, m);
        } else {
            update(2*idx+2, pos, c, m+1, r);
        }
        st[idx]->merge(st[2*idx+1], st[2*idx+2]);
    }

    vector<int> longestRepeating(string s, string C, vector<int>& I) {
        vector<int> res;
        int N = s.size();
        st.resize(4*N);
        buildST(s, 0, 0, N-1);
        for(int i = 0; i < C.size(); i++) {
            update(0, I[i], C[i], 0, N-1);
            res.push_back(st[0]->maxLen);
        }
        return res;
        
    }
};
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