bool isPostorder(const vector<int> &v, int l , int r){
if( l==r || l+1 == r) return true;
int root = v[r], i=l, mid;
while(i<r && v[i]<root) i++;
mid = i;
while(i < r && v[i] > root) i++;
if(i != r) return false;
if(mid == r || mid == l) return isPostorder(v, l ,r-1);
else return (isPostorder(v, l, mid-1) && (isPostorder(v, mid, r-1)) );
}
// ====================²âÊÔ´úÂë====================
void Test(char* testName, int sequence[], int length, bool expected)
{
if(testName != NULL)
printf("%s begins: ", testName);
if(isPostorder(sequence, length) == expected)
printf("passed.\n");
else
printf("failed.\n");
}
bool isPostorder(int* array, int length)
{
if(array == NULL || length <= 0)
{
return false;
}
int root = array[length-1];
int i = 0;
for(; i < length - 1; i++)
{
if(array[i] > root)
{
break;
}
}
int j = i;
for(; j < length - 1; j++)
{
if(array[j] < root)
{
return false;
}
}
//ÅжÏ×ó×ÓÊ÷ÊÇ·ñΪ¶þ²æËÑË÷Ê÷
bool left = true;
if(i > 0)
{
left = isPostorder(array, i);
}
bool right = true;
if(i < length - 1)
{
right = isPostorder(array + i, length- 1 - i);
}
//ÅжÏÓÒ×ÓÊ÷ÊÇ·ñΪ¶þ²æËÑË÷Ê÷
return (left && right);
}
bool VerifySquenceOfBST(vector<int> sequence) {
if(sequence.size() == 0) return false;
else return isPostorder(sequence, 0, sequence.size()-1);
}
