Create 2096. Step-By-Step Directions From a Binary Tree Node to Another

2096. Step-By-Step Directions From a Binary Tree Node to Another

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+/**
+ * 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:
+
+    void f(TreeNode *root,bool &get,string &str,int st){
+        if(get){
+            str.pop_back();
+            return;
+        }
+        if(!root){
+            str.pop_back();
+            return;
+        }
+        if(root->val == st){
+            get = true;
+            return;
+        }
+        str+='L';
+        f(root->left,get,str,st);
+        if(get) return;
+        str+='R';
+        f(root->right,get,str,st);
+        if(get) return;
+        str+='U';
+        str.pop_back();
+        str.pop_back();
+    }
+    string getDirections(TreeNode* root, int startValue, int destValue) {
+        bool get = false;
+        string ststr = "",endstr="",ans="";
+        f(root,get,ststr,startValue);
+        get = false;
+        f(root,get,endstr,destValue);
+        if(ststr==""){
+            return endstr;
+        }
+        if(endstr==""){
+            for(int i=0;i<ststr.size();i++){
+                if(ststr[i]=='L' || ststr[i]=='R'){
+                    ststr[i]='U';
+                }
+            }
+            return ststr;
+        }
+        if(ststr[0]==endstr[0]){
+            string st,end;
+            int i=1;
+            while(i<min(ststr.size(),endstr.size())){
+                if(ststr[i]==endstr[i]){
+                    i++;
+                }
+                else{
+                    break;
+                }
+            }
+            if(i<min(ststr.size(),endstr.size())){
+                int j = i,k=i;
+                while(i<ststr.size()){
+                    ststr[i]='U';
+                    i++;
+                }
+                return ststr.substr(k,ststr.size()) + endstr.substr(j,endstr.size());
+            }
+            else{
+                if(i==ststr.size()){
+                    return endstr.substr(i,endstr.size());
+                }
+                else{
+                    int j = i;
+                    while(i<ststr.size()){
+                        ststr[i] = 'U';
+                        i++;
+                    }
+                    return ststr.substr(j,ststr.size());
+                }
+            }
+        }
+        string temp;
+        for(int i=0;i<ststr.size();i++){
+            temp+='U';
+        }
+        temp+=endstr;
+        return temp;
+    }
+};