LeetCode Symmetric Tree非递归

镜像二叉树BFS
成对压入队列

bool isSymmetric(TreeNode* root) {
        if(!root) return true;
        queue<TreeNode*> que;
        que.push(root -> left);
        que.push(root -> right);
        while(!que.empty()) {
            TreeNode* t1 = que.front();
            que.pop();
            TreeNode* t2 = que.front();
            que.pop();
            if(t1 == t2) continue;
            if(!t1 || !t2 || t1 -> val != t2 -> val) return false;
            que.push(t1 -> left);
            que.push(t2 -> right);
            que.push(t1 -> right);
            que.push(t2 -> left);
        }
        return true;
    }