Given two binary trees, write a function to check if they are equal or not.
Two binary trees are considered equal if they are structurally identical and the nodes have the same value.
題意：判斷兩個樹镇防，形狀和各個節(jié)點上的值是否完全相同。
java代碼：
public boolean isSameTree(TreeNode p, TreeNode q) {
if(p == null && q == null){
return true;
}
if (p == null || q == null) {
return false;
}
if (p.val == q.val) {
return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}else {
return false;
}
}
