<p>You are given the <code>root</code> of a <strong>binary tree</strong> with <code>n</code> nodes. Each node is uniquely assigned a value from <code>1</code> to <code>n</code>. You are also given an integer <code>startValue</code> representing the value of the start node <code>s</code>, and a different integer <code>destValue</code> representing the value of the destination node <code>t</code>.</p>

<p>Find the <strong>shortest path</strong> starting from node <code>s</code> and ending at node <code>t</code>. Generate step-by-step directions of such path as a string consisting of only the <strong>uppercase</strong> letters <code>&#39;L&#39;</code>, <code>&#39;R&#39;</code>, and <code>&#39;U&#39;</code>. Each letter indicates a specific direction:</p>

<ul>
	<li><code>&#39;L&#39;</code> means to go from a node to its <strong>left child</strong> node.</li>
	<li><code>&#39;R&#39;</code> means to go from a node to its <strong>right child</strong> node.</li>
	<li><code>&#39;U&#39;</code> means to go from a node to its <strong>parent</strong> node.</li>
</ul>

<p>Return <em>the step-by-step directions of the <strong>shortest path</strong> from node </em><code>s</code><em> to node</em> <code>t</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/11/15/eg1.png" style="width: 214px; height: 163px;" />
<pre>
<strong>Input:</strong> root = [5,1,2,3,null,6,4], startValue = 3, destValue = 6
<strong>Output:</strong> &quot;UURL&quot;
<strong>Explanation:</strong> The shortest path is: 3 &rarr; 1 &rarr; 5 &rarr; 2 &rarr; 6.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/11/15/eg2.png" style="width: 74px; height: 102px;" />
<pre>
<strong>Input:</strong> root = [2,1], startValue = 2, destValue = 1
<strong>Output:</strong> &quot;L&quot;
<strong>Explanation:</strong> The shortest path is: 2 &rarr; 1.
</pre>

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

<ul>
	<li>The number of nodes in the tree is <code>n</code>.</li>
	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
	<li><code>1 &lt;= Node.val &lt;= n</code></li>
	<li>All the values in the tree are <strong>unique</strong>.</li>
	<li><code>1 &lt;= startValue, destValue &lt;= n</code></li>
	<li><code>startValue != destValue</code></li>
</ul>

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
TreeNode* lowestCommonAncestor(TreeNode* &root, int &p,int& q) {
        if(root==NULL){
            return NULL;
        }
        if(root->val==p){
            return root;
        }
        if(root->val==q){
            return root;
        }
        TreeNode*leftAns=lowestCommonAncestor(root->left,p,q);
        TreeNode*rightAns=lowestCommonAncestor(root->right,p,q);
        if(leftAns==NULL&&rightAns==NULL){
            return NULL;
        }
        else if(leftAns!=NULL&&rightAns==NULL){
            return leftAns;
        }
        else if(leftAns==NULL&&rightAns!=NULL){
            return rightAns;
        }
        else{
            return root;
        }
    }
   int solve(int s,TreeNode*&d,int count){
    if(d==nullptr){
        return 0;
    }
        if(d->val==s){
            return count;
        }
        int left = solve(s,d->left,count+1);
        int right= solve(s,d->right,count+1);
        if(left!=0){
            return left;
        }
        else {
            return right;
        }


    }
    TreeNode*info=NULL;
    string solve(TreeNode*&lca,int &dest,string &str){
        if(lca==nullptr){
            return "";
        }
        if(lca->val==dest){
            info=lca;
            return str;
        }
        str.push_back('L');
        string left = solve(lca->left,dest,str);
        if(info==NULL)
        str.pop_back();
        str.push_back('R');
        string right = solve(lca->right,dest,str);
         if(info==NULL)
       str.pop_back();
        if(left==""&&right==""){
            return "";
        }
      else  if(left!=""){
            return left;
        }
    else{
        return right;
    }
    }
    string getDirections(TreeNode* root, int startValue, int destValue) {
      TreeNode* lca=  lowestCommonAncestor(root,startValue,destValue);
        cout<<lca->val;
        int count=0;
        if(lca->val==destValue){
          int countAns=  solve(startValue,lca,count);
          string s="";
          while(countAns--){
            s.push_back('U');
          }
          return s;
        }
        else if(lca->val==startValue){
            string str;
            string AnsRight=solve(lca,destValue,str);
            return AnsRight;
        }
        else{
            int countAns=  solve(startValue,lca,count);
            string s="";
          while(countAns--){
            s.push_back('U');
          }
          string ansBoth=solve(lca,destValue,s);
          return ansBoth;
        }
        return "as";
    }
};
154408