LeetCode-第251场周赛

yfx

July 25, 2021

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510 words

算法 C/C++ Python

# Problem A - [字符串转化后的各位数字之和](https://leetcode-cn.com/problems/sum-of-digits-of-string-after-convert/)

## 方法一：模拟

> 按照题意模拟即可

### 比赛中代码：

```cpp
class Solution {
public:
    int getLucky(string s, int k) {
        int a[26];
        for (int i = 0; i < 26; ++ i) a[i] = i + 1;
        string t = "";
        for (auto c : s) {
            int id = c - 'a';
            t += to_string(a[id]);
        }
        while (k -- ) {
            //cout << t << endl;
            int tm = 0;
            for (auto c : t) {
                tm += c - '0';
            }
            t = to_string(tm);
        }
        int ans = 0;
        for (auto c : t) {
            ans = ans * 10 + c - '0';
        }
        return ans;
    }
};
```

~~ps：STL还是用的不够熟练，还有很大进步空间~~

### 赛后优化代码：

<div class="tab-container post_tab box-shadow-wrap-lg">
<ul class="nav no-padder b-b scroll-hide" role="tablist">
<li class='nav-item active' role="presentation"><a class='nav-link active' style="" data-toggle="tab" 
aria-controls='tabs-1ae38be11229eccdfb62fbf094a2febd870' role="tab" data-target='#tabs-1ae38be11229eccdfb62fbf094a2febd870'>**C++**</a></li><li class='nav-item ' role="presentation"><a class='nav-link ' style="" data-toggle="tab" 
aria-controls='tabs-607857dd93df2858066eb8b6ca093af8611' role="tab" data-target='#tabs-607857dd93df2858066eb8b6ca093af8611'>**Python 3**</a></li>
</ul>
<div class="tab-content no-border">
<div role="tabpanel" id='tabs-1ae38be11229eccdfb62fbf094a2febd870' class="tab-pane fade active in">

```cpp
class Solution {
public:
    int getLucky(string s, int k) {
        string ans;
        for (char c : s) ans += to_string(c - 96);
        while (k -- ) {
            int sum = 0;
            for (char c : ans) sum += c - '0';
            ans = to_string(sum);
        }
        return stoi(ans);
    }
};
```

</div><div role="tabpanel" id='tabs-607857dd93df2858066eb8b6ca093af8611' class="tab-pane fade  ">

```python
class Solution:
    def getLucky(self, s: str, k: int) -> int:
        snum = ''.join(map(lambda x : str(ord(x) - 96), s))
        for _ in range(k):
            snum = str(sum(map(int, snum)))
        return int(snum)
```

~~ps：除了Python牛皮咱还能说啥？~~

</div>
</div>
</div>

### 复杂度分析：

* 时间复杂度：$O(k|S|)$
* 空间复杂度：$O(|S|)$

Last modification：August 18, 2021