题目描述
输入一个整数数组,判断该数组是不是某二叉搜索树的后序遍历的结果。如果是则输出Yes,否则输出No。假设输入的数组的任意两个数字都互不相同。
class Solution { public: bool VerifySquenceOfBST(vector<int> sequence) { int size = sequence.size(); if(0==size) { return false; } return isLastOrder(sequence, 0, size-1); } private: bool isLastOrder(vector<int>& sequece, int b, int e) { if(b==e) { return true; } int mid = b; while(sequece[mid++]<sequece[e] && mid<e); int tmp = mid; while (sequece[tmp++]>sequece[e] && tmp<e); if(tmp<e) { return false; } if(mid==b || mid==e) { return isLastOrder(sequece, b, e-1); } else { return (isLastOrder(sequece, b, mid-1) && isLastOrder(sequece, mid, e-1)); } } };*/ //非递归 class Solution { public: bool VerifySquenceOfBST(vector<int> sequence) { int size = sequence.size(); if(0==size)return false; int i = 0; while(--size) { while(sequence[i++]<sequence[size]); while(sequence[i++]>sequence[size]); if(i<size)return false; i=0; } return true; } }; |