###### tags: `Weekly Contest`
# Weekly Contest 420

## [3324. Find the Sequence of Strings Appeared on the Screen](https://leetcode.com/problems/find-the-sequence-of-strings-appeared-on-the-screen/) (<font color=#FFC011>Medium</font>)

### Solution
暴力解，就這樣。

#### 時間複雜度: $O(n^2)$

#### 空間複雜度: $O(n^2)$

程式碼:

class Solution {
public:
    vector<string> stringSequence(string target) {
        vector<string> results;
        string temp;
        for (int i = 0; i < target.size(); i++) {
            for (int j = int('a'); j <= target[i]; j++) {
                temp.push_back(char(j));
                results.push_back(temp);
                temp.pop_back();
            }
            temp.push_back(target[i]);
        }
        return results;
    }
};

## [3325. Count Substrings With K-Frequency Characters I](https://leetcode.com/problems/count-substrings-with-k-frequency-characters-i/) (<font color=#FFC011>Medium</font>)

### Solution

#### 時間複雜度:

#### 空間複雜度:

程式碼:

## [3326. Minimum Division Operations to Make Array Non Decreasing](https://leetcode.com/problems/minimum-division-operations-to-make-array-non-decreasing/) (<font color=#FFC011>Medium</font>)

### Solution

#### 時間複雜度:

#### 空間複雜度:

程式碼:

## [3327. Check if DFS Strings Are Palindromes](https://leetcode.com/problems/check-if-dfs-strings-are-palindromes/) (<font color=#FF375F>Hard</font>)

### Solution

#### 時間複雜度:

#### 空間複雜度:

程式碼: