boolean vertify(int[] sequence,int length)
{
if(sequence == null||length<0)
return false;
int root = sequence[length-1];
int i = 0;
for (; i < length-1; i++)
{
if(sequence[i]>root)
break;
}
int j = i;
for (; j < length-1; j++)
{
if(sequence[j]<root)
return false;
}
boolean left = true;
if(i>0)
left = vertify(sequence, i);
boolean right = true;
if(i<length-1)
right = vertify(sequence, length-i-1);
return left&&right;
}