Same Tree

bool isSameTree(TreeNode p, TreeNode q) {

stack<TreeNode*> s;

TreeNode a,b;

s.push(p);

s.push(q);

while(!s.empty()){

a=s.top();

s.pop();

b=s.top();

s.pop();

if(!a&&!b) //剪枝

continue;

if(!a||!b)

return false;

if(a->val!=b->val)

return false;

s.push(a->left);

s.push(b->left);

s.push(a->right);

s.push(b->right);

}

return true;

}