剑指offer-二叉树的深度

/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};*/
class Solution {
public:
int TreeDepth(TreeNode* pRoot)
{
if(pRoot == NULL){
return 0;
}
stack<TreeNode*> st;
stack<bool> fst;
TreeNode *top = pRoot;
bool ftop;
int maxDepth = 0;
while(top != NULL || !st.empty()){
while(top != NULL){
st.push(top);
fst.push(true);
top = top->left;
}

top = st.top();
ftop = fst.top();

st.pop();
fst.pop();
if(ftop){
st.push(top);
fst.push(false);

if(top->right == NULL && st.size() > maxDepth){
maxDepth = st.size();
}
top = top->right;
}else{
top = NULL;
}

}

return maxDepth;
}
};