988. Smallest String Starting From Leaf

Author: amitbansal7

smallest-string-starting-from-leaf.cpp

@@ -0,0 +1,20 @@
+// Runtime: 8 ms
+// Memory Usage: 20 MB
+class Solution {
+public:
+  void solve(TreeNode* root, string t, string &res) {
+    if (!root) return;
+    t = (char)(root->val + 'a') + t;
+    solve(root->left, t, res);
+    solve(root->right, t, res);
+    if (!root->left && !root->right && t < res) {
+      res = t;
+    }
+  }
+
+  string smallestFromLeaf(TreeNode* root) {
+    string res = "~";
+    solve(root, "", res);
+    return res;
+  }
+};