update: 添加问题“3120.统计特殊字母的数量I”的代码和题解 (#1607)

3120: AC.cpp (#1606) - AC,22.22%,57.14% + (en)

Signed-off-by: LetMeFly666 <Tisfy@qq.com>

Author: LetMeFly666

.commitmsg

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+3120: AC.cpp (#1606) - AC,22.22%,57.14% + (en)

Codes/3120-count-the-number-of-special-characters-i.cpp

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+/*
+ * @Author: LetMeFly
+ * @Date: 2026-05-26 23:50:43
+ * @LastEditors: LetMeFly.xyz
+ * @LastEditTime: 2026-05-26 23:53:14
+ */
+#ifdef _DEBUG
+#include "_[1,2]toVector.h"
+#endif
+
+class Solution {
+public:
+    int numberOfSpecialChars(string word) {
+        bool lower[26] = {false}, upper[26] = {false};
+        for (char c : word) {
+            if ('a' <= c && c <= 'z') {
+                lower[c - 'a'] = true;
+            } else {
+                upper[c - 'A'] = true;
+            }
+        }
+
+        int ans = 0;
+        for (int i = 0; i < 26; i++) {
+            ans += lower[i] && upper[i];
+        }
+        return ans;
+    }
+};

README.md

@@ -1057,6 +1057,7 @@
 |3110.字符串的分数|简单|<a href="https://leetcode.cn/problems/score-of-a-string/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2025/03/15/LeetCode%203110.%E5%AD%97%E7%AC%A6%E4%B8%B2%E7%9A%84%E5%88%86%E6%95%B0/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/146275888" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/score-of-a-string/solutions/3612406/letmefly-3110zi-fu-chuan-de-fen-shu-mo-n-aqpo/" target="_blank">LeetCode题解</a>|
 |3112.访问消失节点的最少时间|中等|<a href="https://leetcode.cn/problems/minimum-time-to-visit-disappearing-nodes/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2024/07/18/LeetCode%203112.%E8%AE%BF%E9%97%AE%E6%B6%88%E5%A4%B1%E8%8A%82%E7%82%B9%E7%9A%84%E6%9C%80%E5%B0%91%E6%97%B6%E9%97%B4/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/140530368" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/minimum-time-to-visit-disappearing-nodes/solutions/2848666/letmefly-3112fang-wen-xiao-shi-jie-dian-1cgwc/" target="_blank">LeetCode题解</a>|
 |3115.质数的最大距离|中等|<a href="https://leetcode.cn/problems/maximum-prime-difference/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2024/07/02/LeetCode%203115.%E8%B4%A8%E6%95%B0%E7%9A%84%E6%9C%80%E5%A4%A7%E8%B7%9D%E7%A6%BB/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/140121329" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/maximum-prime-difference/solutions/2828631/letmefly-3115zhi-shu-de-zui-da-ju-chi-zh-1yvd/" target="_blank">LeetCode题解</a>|
+|3120.统计特殊字母的数量I|简单|<a href="https://leetcode.cn/problems/count-the-number-of-special-characters-i/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2026/05/26/LeetCode%203120.%E7%BB%9F%E8%AE%A1%E7%89%B9%E6%AE%8A%E5%AD%97%E6%AF%8D%E7%9A%84%E6%95%B0%E9%87%8FI/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/161432822" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/count-the-number-of-special-characters-i/solutions/3974744/letmefly-3120tong-ji-te-shu-zi-mu-de-shu-bata/" target="_blank">LeetCode题解</a>|
 |3127.构造相同颜色的正方形|简单|<a href="https://leetcode.cn/problems/make-a-square-with-the-same-color/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2024/08/31/LeetCode%203127.%E6%9E%84%E9%80%A0%E7%9B%B8%E5%90%8C%E9%A2%9C%E8%89%B2%E7%9A%84%E6%AD%A3%E6%96%B9%E5%BD%A2/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/141756605" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/make-a-square-with-the-same-color/solutions/2899199/letmefly-3127gou-zao-xiang-tong-yan-se-d-xp4l/" target="_blank">LeetCode题解</a>|
 |3131.找出与数组相加的整数I|简单|<a href="https://leetcode.cn/problems/find-the-integer-added-to-array-i/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2024/08/08/LeetCode%203131.%E6%89%BE%E5%87%BA%E4%B8%8E%E6%95%B0%E7%BB%84%E7%9B%B8%E5%8A%A0%E7%9A%84%E6%95%B4%E6%95%B0I/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/141037760" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/find-the-integer-added-to-array-i/solutions/2873708/letmefly-3131zhao-chu-yu-shu-zu-xiang-ji-mfd3/" target="_blank">LeetCode题解</a>|
 |3132.找出与数组相加的整数II|中等|<a href="https://leetcode.cn/problems/find-the-integer-added-to-array-ii/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2024/08/09/LeetCode%203132.%E6%89%BE%E5%87%BA%E4%B8%8E%E6%95%B0%E7%BB%84%E7%9B%B8%E5%8A%A0%E7%9A%84%E6%95%B4%E6%95%B0II/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/141072842" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/find-the-integer-added-to-array-ii/solutions/2874942/letmefly-3132zhao-chu-yu-shu-zu-xiang-ji-eljs/" target="_blank">LeetCode题解</a>|

Solutions/LeetCode 3120.统计特殊字母的数量I.md

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+---
+title: 3120.统计特殊字母的数量 I：(手写)哈希表
+date: 2026-05-26 23:55:19
+tags: [题解, LeetCode, 简单, 哈希表, set, 字符串]
+categories: [题解, LeetCode]
+---
+
+# 【LetMeFly】3120.统计特殊字母的数量 I：(手写)哈希表
+
+力扣题目链接：[https://leetcode.cn/problems/count-the-number-of-special-characters-i/](https://leetcode.cn/problems/count-the-number-of-special-characters-i/)
+
+<p>给你一个字符串 <code>word</code>。如果 <code>word</code> 中同时存在某个字母的小写形式和大写形式，则称这个字母为 <strong>特殊字母</strong> 。</p>
+
+<p>返回 <code>word</code> 中<strong> </strong><strong>特殊字母 </strong>的数量。</p>
+
+<p>&nbsp;</p>
+
+<p><strong class="example">示例 1:</strong></p>
+
+<div class="example-block">
+<p><strong>输入：</strong><span class="example-io">word = "aaAbcBC"</span></p>
+
+<p><strong>输出：</strong><span class="example-io">3</span></p>
+
+<p><strong>解释：</strong></p>
+
+<p><code>word</code> 中的特殊字母是 <code>'a'</code>、<code>'b'</code> 和 <code>'c'</code>。</p>
+</div>
+
+<p><strong class="example">示例 2:</strong></p>
+
+<div class="example-block">
+<p><strong>输入：</strong><span class="example-io">word = "abc"</span></p>
+
+<p><strong>输出：</strong><span class="example-io">0</span></p>
+
+<p><strong>解释：</strong></p>
+
+<p><code>word</code> 中不存在大小写形式同时出现的字母。</p>
+</div>
+
+<p><strong class="example">示例 3:</strong></p>
+
+<div class="example-block">
+<p><strong>输入：</strong><span class="example-io">word = "abBCab"</span></p>
+
+<p><strong>输出：</strong>1</p>
+
+<p><strong>解释：</strong></p>
+
+<p><code>word</code> 中唯一的特殊字母是 <code>'b'</code>。</p>
+</div>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 &lt;= word.length &lt;= 50</code></li>
+	<li><code>word</code> 仅由小写和大写英文字母组成。</li>
+</ul>
+
+
+    
+## 解题方法：哈希表
+
+遍历一般字符串并把所有出现过的字符放入哈希表中，从0到25遍历这26个字母，看哪个字母的大小写都出现过。
+
+有办法使用数组代替(作为)哈希表吗？以及有办法使用52长度的数组作为哈希表吗？有，判断下大小写放入数组对应的位置就好。
+
++ 时间复杂度$O(len(word)+C)$，其中$C=26\times 2$
++ 空间复杂度$O(C)$
+
+### AC代码
+
+#### C++
+
+```cpp
+/*
+ * @LastEditTime: 2026-05-26 23:53:14
+ */
+class Solution {
+public:
+    int numberOfSpecialChars(string word) {
+        bool lower[26] = {false}, upper[26] = {false};
+        for (char c : word) {
+            if ('a' <= c && c <= 'z') {
+                lower[c - 'a'] = true;
+            } else {
+                upper[c - 'A'] = true;
+            }
+        }
+
+        int ans = 0;
+        for (int i = 0; i < 26; i++) {
+            ans += lower[i] && upper[i];
+        }
+        return ans;
+    }
+};
+```
+
+> 同步发文于[CSDN](https://letmefly.blog.csdn.net/article/details/161432822)和我的[个人博客](https://blog.letmefly.xyz/)，原创不易，转载经作者同意后请附上[原文链接](https://blog.letmefly.xyz/2026/05/26/LeetCode%203120.%E7%BB%9F%E8%AE%A1%E7%89%B9%E6%AE%8A%E5%AD%97%E6%AF%8D%E7%9A%84%E6%95%B0%E9%87%8FI/)哦~
+>
+> 千篇源码题解[已开源](https://github.com/LetMeFly666/LeetCode)

test.cpp

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+<!--
+ * @Author: LetMeFly
+ * @Date: 2026-05-26 23:54:27
+ * @LastEditors: LetMeFly.xyz
+ * @LastEditTime: 2026-05-26 23:54:34
+-->
+todo: merge confilct
+
+今日扇贝单词web端改版了