<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* find(TreeNode*root,int x){
    queue<TreeNode*>q;
    q.push(root);
    while(!q.empty()){
        auto p=q.front();
        q.pop();
        TreeNode* node=p;
        if(node->val==x){
            return node;
        }
        if(node->left){
            q.push(node->left);
        }
        if(node->right){
            q.push(node->right);
        }
    }
    return NULL;
}
void parent (map<TreeNode*,TreeNode*> &m,TreeNode*root){
    if(root==NULL){
        return;
    }
    if(root->right){
        m[root->right]=root;
        parent(m,root->right);
    }
    if(root->left){
        m[root->left]=root;
        parent(m,root->left);
    }
}
    int amountOfTime(TreeNode* root, int start) {
        if(root==NULL){
            return 0;
        }
        TreeNode* target=find(root,start);
         if (target == nullptr) return 0;
        map<TreeNode*,TreeNode*>m;
        parent(m,root);
        queue<TreeNode*>q;
        map<TreeNode*,bool>vis;
        q.push(target);
        vis[target]=true;
        int ans=0;
        while(!q.empty()){
            int n=q.size();
            for(int i=0;i<n;i++){
                auto p=q.front();
                TreeNode* node=p;
                q.pop();
                if(node->left && !vis[node->left]){
                    q.push(node->left);
                    vis[node->left]=true;
                }
                if(node->right!=NULL && vis[node->right]!=true){
                    q.push(node->right);
                    vis[node->right]=true;
                }
                if(m[node]!=NULL && vis[m[node]]!=true){
                    q.push(m[node]);
                    vis[m[node]]=true;
                }
            }
            ans++;
        }
        return ans-1;
    }
};
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