###### tags: `Weekly Contest`
# Weekly Contest 406

## [3216. Lexicographically Smallest String After a Swap](https://leetcode.com/problems/lexicographically-smallest-string-after-a-swap) (<font color=#00B8A3>Easy</font>)

限制 :

<ul>
<li>2 <= s.length <= 100</li>
<li>s consists only of digits.</li>
</ul>
### Solution

#### 時間複雜度: $O(n)$

#### 空間複雜度: $O(1)$

程式碼:

class Solution {
public:
    string getSmallestString(string s) {
        for (int i = 0; i < s.size() - 1; i++) {
            if (s[i] % 2 == s[i + 1] % 2 && s[i] > s[i + 1]) {
                swap(s[i], s[i + 1]);
                break;
            }
        }
        return s;
    }
};

## [3217. Delete Nodes From Linked List Present in Array](https://leetcode.com/problems/delete-nodes-from-linked-list-present-in-array) (<font color=#FFC011>Medium</font>)

限制 :
<ul>
<li><code>1 <= nums.length <= 10⁵</code></li>
<li><code>1 <= nums[i] <= 10⁵</code></li>
<li><code>All elements in nums are unique.</code></li>
<li><code>The number of nodes in the given list is in the range [1, 10⁵].</code></li>
<li><code>1 <= Node.val <=10⁵</code></li>
<li><code>The input is generated such that there is at least one node in the linked list that has a value not present in nums.</code></li>
</ul>

### Solution

#### 時間複雜度: $O()$

#### 空間複雜度: $O()$

程式碼:

class Solution {
public:
    ListNode* modifiedList(vector<int>& nums, ListNode* head) {
        unordered_set<int> numss(nums.begin(), nums.end());
        while (numss.find(head-> val) != numss.end()) {
            head = head->next;
        }
        ListNode* left = head;
        while (left && left->next != nullptr) {
            ListNode* right = left->next;
            while (right && numss.find(right->val) != numss.end()) {
                left->next = right->next;
                right = right->next;
            }
            left = right;
        }
        return head;
    }
};

## [3]()(<font color=#FFC011>Medium</font>)

限制 :

<ul>
<li><code>10⁴</code></li>
</ul>
### Solution

#### 時間複雜度: $O()$

#### 空間複雜度: $O()$

程式碼:

## [4]()(<font color=#FF375F>Hard</font>)

限制 :

<ul>
<li><code>10⁴</code></li>
</ul>
### Solution

#### 時間複雜度: $O()$

#### 空間複雜度: $O()$

程式碼: