chore: add daily leetcode post 2309兼具大小写的最好英文字母_translated

Author: longsizhuo

app/docs/CommunityShare/Leetcode/2309兼具大小写的最好英文字母_translated.md

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+---
+title: 2309. The best English letters with both appropriates and lowercases One question daily
+date: '2024.01.01 0:00'
+tags:
+  - - Python
+  - - answer
+  - - One question daily
+  - - Bit operation
+  - - Hash table
+  - - C++
+abbrlink: b4953d62
+---
+
+[2309. The best English letters with both appropriates and lowercases](https://leetcode.cn/problems/greatest-english-letter-in-upper-and-lower-case/description/)
+
+# Thought：
+
+1. Hash table：The first thing to think of the question is to solve it with a dictionary。But find that you can directly traverse the alphabet，fromZStart looking for，See if the applause exists，Just return directly。
+
+*Running time exceeds99.9%*
+2. Bit operation：We can use two integers mask1 and mask2 Record string separately s 中出现的小写字母and大写字母，in mask1 First i 
+Position representation i Does a lowercase letter appear，and mask2 First i Position representation i Whether an uppercase letter appears。
+
+Then we will mask1 and mask2 Perform and calculate，The results obtained mask First i Position representation i Whether the lethals of the letter appear at the same time。
+
+As long as you get mask The highest level of binary representation 1 s position，Convert it to the corresponding capital letter。If all binary positions are not 1，Explain that there is no letter that appears at the same time,，Return to an empty string。
+
+>author：ylb
+Link：https://leetcode.cn/problems/greatest-english-letter-in-upper-and-lower-case/solutions/2077636/by-lcbin-zbg0/
+source：Deduction（LeetCode）
+著作权归author所有。商业转载请联系author获得授权，Non -commercial reprint Please indicate the source。
+
+# Code：
+
+```python Traversing the alphabet
+class Solution:
+    def greatestLetter(self, s: str) -> str:
+        for i in range(90, 64, -1):
+            if chr(i) in s and chr(i+32) in s:
+                return chr(i)
+        return ""
+```
+```C++  Hash table
+class Solution {
+public:
+    string greatestLetter(string s) {
+        unordered_set<char> strin(s.begin(),s.end());
+        for(char c = 'Z'; c >= 'A'; --c){
+            if(strin.count(c) && strin.count(char(c+32))){
+                return string(1,c);
+            }
+        }
+        return "";
+    }
+};
+```
+```python  Bit operation
+class Solution:
+    def greatestLetter(self, s: str) -> str:
+        # We can use two integers mask1 and mask2
+        # Record string separately s 中出现的小写字母and大写字母，in mask1 First i Position representation i Does a lowercase letter appear，
+            # and mask2 First i Position representation i Whether an uppercase letter appears。
+        mask1 = mask2 = 0
+        for i in s:
+            if i.islower():
+                mask1 |= 1 << (ord(i) - ord("a"))
+            else:
+                mask2 |= 1 << (ord(i) - ord("A"))
+        mask = mask1 & mask2
+        return chr(mask.bit_length() - 1 + ord("A")) if mask else ""
+```
+