标签：笔试题
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。
public boolean VerifySquenceOfBST(int [] sequence) { if(sequence.length==0) return false; if(sequence.length==1) return true; return ju(sequence, 0, sequence.length-1); } public boolean ju(int[] a,int star,int root){ if(star>=root) return true; int i = root; //从后面开始找 while(i>star&&a[i-1]>a[root]) i--;//找到比根小的坐标 //从前面开始找 star到i-1应该比根小 for(int j = star;j<i-1;j++) if(a[j]>a[root]) return false;; return ju(a,star,i-1)&&ju(a, i, root-1); }}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;
}
}; |
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标签：笔试题
原文地址：http://10541556.blog.51cto.com/10531556/1851325
