100. Same Tree
题意
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.
递归解法
class Solution {
public:
bool isSameTree(TreeNode *p, TreeNode *q) {
if(p == NULL&& !q){
return true;
}
if(!p|| !q){
return false;
}
return p->val == q->val && isSameTree(p->left,q->left) && isSameTree(p->right,q->right);
}
};
非递归解法
class Solution {
public:
bool isSameTree(TreeNode *p, TreeNode *q) {
stack<TreeNode*> s;
s.push(p);
s.push(q);
while(!s.empty()) {
p = s.top(); s.pop();
q = s.top(); s.pop();
if (!p && !q) continue;
if (!p || !q) return false;
if (p->val != q->val) return false;
s.push(p->left);
s.push(q->left);
s.push(p->right);
s.push(q->right);
}
return true;
}
};
