剑指offer 面试题24 判断二叉搜索树后续遍历序列

bool IsBSTSquence(const int *sequence,int len){
bool result=false;
if(sequence==NULL||len<=0)
return result;

const int *flag=sequence;
int rootdata=*(sequence+len-1);
while(*flag<rootdata)){
++flag;
}
for(int i=0;flag+i<sequence+len-1;++i){
if(*(flag+i)<rootdata)
return result;
}

bool left=true;
if(flag>sequence)
left=IsBSTSquence(sequence,flag-sequence);

bool right=true;
if(flag<sequence+len-1)
right=IsBSTSquence(flag,sequence+len-1-flag);

if(left&&right)
result=true;
return result;
}