<p>You are given the <code>root</code> of a binary tree with <strong>unique</strong> values, and an integer <code>start</code>. At minute <code>0</code>, an <strong>infection</strong> starts from the node with value <code>start</code>.</p>

<p>Each minute, a node becomes infected if:</p>

<ul>
	<li>The node is currently uninfected.</li>
	<li>The node is adjacent to an infected node.</li>
</ul>

<p>Return <em>the number of minutes needed for the entire tree to be infected.</em></p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2022/06/25/image-20220625231744-1.png" style="width: 400px; height: 306px;" />
<pre>
<strong>Input:</strong> root = [1,5,3,null,4,10,6,9,2], start = 3
<strong>Output:</strong> 4
<strong>Explanation:</strong> The following nodes are infected during:
- Minute 0: Node 3
- Minute 1: Nodes 1, 10 and 6
- Minute 2: Node 5
- Minute 3: Node 4
- Minute 4: Nodes 9 and 2
It takes 4 minutes for the whole tree to be infected so we return 4.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2022/06/25/image-20220625231812-2.png" style="width: 75px; height: 66px;" />
<pre>
<strong>Input:</strong> root = [1], start = 1
<strong>Output:</strong> 0
<strong>Explanation:</strong> At minute 0, the only node in the tree is infected so we return 0.
</pre>

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

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
	<li><code>1 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
	<li>Each node has a <strong>unique</strong> value.</li>
	<li>A node with a value of <code>start</code> exists in the tree.</li>
</ul>

class Solution {
public:
    TreeNode* parentchild(TreeNode* root,unordered_map<TreeNode*, TreeNode*>& m, int start) {
        queue<TreeNode*> q;
        q.push(root);
        TreeNode* curr;
        while (!q.empty()) {
            int queuesize = q.size();
            while (queuesize--) {
                TreeNode* temp = q.front();
                q.pop();
                if (temp->val == start) {
                    curr = temp;
                }
                if (temp->left) {
                    q.push(temp->left);
                    m[temp->left] = temp;
                }
                if (temp->right) {
                    q.push(temp->right);
                    m[temp->right] = temp;
                }
            }
        }
        return curr;
    }
    int calculateTime(TreeNode* startnode,unordered_map<TreeNode*,TreeNode*> m){
        int time=0;
        queue<TreeNode*> q;
        set<TreeNode*>infected;
        q.push(startnode);
infected.insert(startnode);
        while (!q.empty()) {
            int queuesize = q.size();
            bool spread=false;
            while (queuesize--) {
                TreeNode* temp = q.front();
                q.pop();
                if (temp->left and !infected.count(temp->left)) {
                    q.push(temp->left);
                    infected.insert(temp->left);
                    spread=true;
                }
                if (temp->right and !infected.count(temp->right)) {
                    q.push(temp->right);
                    infected.insert(temp->right);
                    spread=true;

                }
                if(m.find(temp)!=m.end() and !infected.count(m[temp])){
                    q.push(m[temp]);
                    infected.insert(m[temp]);
                    spread=true;

                }
            }
            if(spread==true)time++;
        }
        return time;
    } 
    int amountOfTime(TreeNode* root,int start) {
        unordered_map<TreeNode*, TreeNode*> m;

        TreeNode* startnode = parentchild(root, m, start);

        return calculateTime(startnode, m);
    }
};
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