24 Post-order traversal sequence of binary search tree

Input an integer array to determine whether the array is the result of a post-order traversal of a binary search tree. If yes, output Yes, otherwise output No. Suppose any two numbers of the input array are different from each other.

 

 

C++:

 1 class Solution {
 2 public:
 3     bool VerifySquenceOfBST(vector<int> sequence) {
 4         if (sequence.empty())
 5             return false ;
 6         return Verify(sequence , 0 , sequence.size()-1) ;
 7     }
 8     
 9     bool Verify(vector<int> sequence,  int left , int right) {
10         if (right - left <= 0)
11             return true ;
12         int rootValue = sequence[right] ;
13         int cutIndex = left ;
14         for(; cutIndex < right ; cutIndex++){
15             if (sequence[cutIndex] > rootValue)
16                 break ;
17         }
18         for(int i = cutIndex ; i < right ; i++){
19             if (sequence[i] < rootValue)
20                 return false ;
21         }
22         return Verify(sequence , left , cutIndex-1) && Verify(sequence , cutIndex , right-1) ;
23     }
24 };