1 problem

Author: hitzzc

README.md

@@ -236,6 +236,7 @@ Golang solution for leetcode. For each problem, there is a simple *_test.go to t
 #### [326. Power of Three](https://github.com/hitzzc/go-leetcode/tree/master/power_of_three)
 #### [327. Count of Range Sum](https://github.com/hitzzc/go-leetcode/tree/master/count_of_range_sum)
 #### [329. Longest Increasing Path in a Matrix](https://github.com/hitzzc/go-leetcode/tree/master/longest_increasing_path_in_a_matrix)
+#### [331. Verify Preorder Serialization of a Binary Tree](https://github.com/hitzzc/go-leetcode/tree/master/verify_preorder_serialization_of_a_binary_tree)
 
 
 

verify_preorder_serialization_of_a_binary_tree/verify_preorder_serialization_of_a_binary_tree.cpp

@@ -0,0 +1,21 @@
+classSolution {
+public:
+boolisValidSerialization(string preorder) {
+int idx = 0;
+returnhelper(preorder, idx) ? idx == preorder.size() ? true : false : false;
+ }
+
+boolhelper(string& preorder, int& idx) {
+if (idx == preorder.size()) returnfalse;
+int start = idx;
+while (idx < preorder.size() && preorder[idx] != ',') ++idx;
+if (idx == preorder.size()) {
+return preorder.substr(start) == "#" ? true : false;
+ }
+ ++idx;
+if (preorder.substr(start, idx-start-1) == "#") 
+returntrue;
+if (!helper(preorder, idx)) returnfalse;
+returnhelper(preorder, idx);
+ }
+};