题目：

题解：

struct TreeNode* deleteNode(struct TreeNode* root, int key){struct TreeNode *cur = root, *curParent = NULL;while (cur && cur->val != key) {curParent = cur;if (cur->val > key) {cur = cur->left;} else {cur = cur->right;}}if (!cur) {return root;}if (!cur->left && !cur->right) {cur = NULL;} else if (!cur->right) {cur = cur->left;} else if (!cur->left) {cur = cur->right;} else {struct TreeNode *successor = cur->right, *successorParent = cur;while (successor->left) {successorParent = successor;successor = successor->left;}if (successorParent->val == cur->val) {successorParent->right = successor->right;} else {successorParent->left = successor->right;}successor->right = cur->right;successor->left = cur->left;cur = successor;}if (!curParent) {return cur;} else {if (curParent->left && curParent->left->val == key) {curParent->left = cur;} else {curParent->right = cur;}return root;}
}