单值二叉树

点击链接做题

代码：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
typedef struct TreeNode TreeNode;
bool isUnivalTree(struct TreeNode* root) {
    if(root == NULL){
        return true;
    }
    //root不为空，把root和root->left,root->right比较
    if(root->left && root->left->val != root->val){
        return false;
    }
    if(root->right && root->right->val != root->val){
        return false;
    }
    //查看左子树和右子树是不是单值二叉树
    return isUnivalTree(root->left) && isUnivalTree(root->right);
}