feat: update leetcode solutions: No.0017. Letter Combinations of a Phone Number

Author: yanglbme

README.md

@@ -69,6 +69,7 @@
 ### 字符串
 
 - [无重复字符的最长子串](/solution/0000-0099/0003.Longest%20Substring%20Without%20Repeating%20Characters/README.md)
+- [最长公共前缀](/solution/0000-0099/0014.Longest%20Common%20Prefix/README.md)
 - [反转字符串中的元音字母](/solution/0300-0399/0345.Reverse%20Vowels%20of%20a%20String/README.md)
 - [字符串转换整数 (atoi)](/solution/0000-0099/0008.String%20to%20Integer%20%28atoi%29/README.md)
 - [赎金信](/solution/0300-0399/0383.Ransom%20Note/README.md)

README_EN.md

@@ -68,6 +68,7 @@ Complete solutions to [LeetCode](https://leetcode-cn.com/problemset/all/), [LCOF
 ### Strings
 
 - [Longest Substring Without Repeating Characters](/solution/0000-0099/0003.Longest%20Substring%20Without%20Repeating%20Characters/README_EN.md)
+- [Longest Common Prefix](/solution/0000-0099/0014.Longest%20Common%20Prefix/README_EN.md)
 - [Reverse Vowels of a String](/solution/0300-0399/0345.Reverse%20Vowels%20of%20a%20String/README_EN.md)
 - [String to Integer (atoi)](/solution/0000-0099/0008.String%20to%20Integer%20%28atoi%29/README_EN.md)
 - [Ransom Note](/solution/0300-0399/0383.Ransom%20Note/README_EN.md)

solution/0000-0099/0017.Letter Combinations of a Phone Number/README.md

@@ -31,15 +31,60 @@
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def letterCombinations(self, digits: str) -> List[str]:
+        n = len(digits)
+        if n == 0:
+            return []
+        chars = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz']
+        strs = [chars[int(d) - 2] for d in digits]
+        res = []
+        for s in strs:
+            if not res:
+                res = list(s)
+            else:
+                cache = []
+                for item in res:
+                    for letter in s:
+                        cache.append(item + letter)
+                res = cache
+        return res
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
-
+class Solution {
+    public List<String> letterCombinations(String digits) {
+        int n;
+        if ((n = digits.length()) == 0) return Collections.emptyList();
+        List<String> chars = Arrays.asList("abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz");
+
+        List<String> strs = new ArrayList<>();
+        for (char c : digits.toCharArray()) {
+            strs.add(chars.get(c - '0' - 2));
+        }
+        List<String> res = new ArrayList<>();
+        for (String str : strs) {
+            if (res.size() == 0) {
+                for (char c : str.toCharArray()) {
+                    res.add(String.valueOf(c));
+                }
+            } else {
+                List<String> cache = new ArrayList<>();
+                for (String item : res) {
+                    for (char c : str.toCharArray()) {
+                        cache.add(item + String.valueOf(c));
+                    }
+                }
+                res = cache;
+            }
+        }
+        return res;
+    }
+}
 ```
 
 ### **...**

solution/0000-0099/0017.Letter Combinations of a Phone Number/README_EN.md

@@ -31,13 +31,58 @@
 ### **Python3**
 
 ```python
-
+class Solution:
+    def letterCombinations(self, digits: str) -> List[str]:
+        n = len(digits)
+        if n == 0:
+            return []
+        chars = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz']
+        strs = [chars[int(d) - 2] for d in digits]
+        res = []
+        for s in strs:
+            if not res:
+                res = list(s)
+            else:
+                cache = []
+                for item in res:
+                    for letter in s:
+                        cache.append(item + letter)
+                res = cache
+        return res
 ```
 
 ### **Java**
 
 ```java
-
+class Solution {
+    public List<String> letterCombinations(String digits) {
+        int n;
+        if ((n = digits.length()) == 0) return Collections.emptyList();
+        List<String> chars = Arrays.asList("abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz");
+
+        List<String> strs = new ArrayList<>();
+        for (char c : digits.toCharArray()) {
+            strs.add(chars.get(c - '0' - 2));
+        }
+        List<String> res = new ArrayList<>();
+        for (String str : strs) {
+            if (res.size() == 0) {
+                for (char c : str.toCharArray()) {
+                    res.add(String.valueOf(c));
+                }
+            } else {
+                List<String> cache = new ArrayList<>();
+                for (String item : res) {
+                    for (char c : str.toCharArray()) {
+                        cache.add(item + String.valueOf(c));
+                    }
+                }
+                res = cache;
+            }
+        }
+        return res;
+    }
+}
 ```
 
 ### **...**

solution/0000-0099/0017.Letter Combinations of a Phone Number/Solution.java

@@ -1,30 +1,29 @@
 class Solution {
     public List<String> letterCombinations(String digits) {
-        char[] cs = digits.toCharArray();
-        List<String> result = new ArrayList<>();
-        for (char a : cs) {
-            char[] charArray;
-            switch (a) {
-                case '2': charArray = new char[]{'a','b','c'}; break;
-                case '3': charArray = new char[]{'d','e','f'}; break;
-                case '4': charArray = new char[]{'g','h','i'}; break;
-                case '5': charArray = new char[]{'j','k','l'}; break;
-                case '6': charArray = new char[]{'m','n','o'}; break;
-                case '7': charArray = new char[]{'p','q','r','s'}; break;
-                case '8': charArray = new char[]{'t','u','v'}; break;
-                case '9': charArray = new char[]{'w','x','y','z'}; break;
-                default: return null;
-            }
-            if (result.size() == 0) {
-                for (char aCharArray : charArray) result.add(String.valueOf(aCharArray));
+        int n;
+        if ((n = digits.length()) == 0) return Collections.emptyList();
+        List<String> chars = Arrays.asList("abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz");
+        
+        List<String> strs = new ArrayList<>();
+        for (char c : digits.toCharArray()) {
+            strs.add(chars.get(c - '0' - 2));
+        }
+        List<String> res = new ArrayList<>();
+        for (String str : strs) {
+            if (res.size() == 0) {
+                for (char c : str.toCharArray()) {
+                    res.add(String.valueOf(c));
+                }
             } else {
                 List<String> cache = new ArrayList<>();
-                for (String string : result) {
-                    for (char aCharArray : charArray) cache.add(string + aCharArray);
+                for (String item : res) {
+                    for (char c : str.toCharArray()) {
+                        cache.add(item + String.valueOf(c));
+                    }
                 }
-                result = cache;
+                res = cache;
             }
         }
-        return result;
+        return res;
     }
-}
+}

solution/0000-0099/0017.Letter Combinations of a Phone Number/Solution.py

@@ -0,0 +1,18 @@
+class Solution:
+    def letterCombinations(self, digits: str) -> List[str]:
+        n = len(digits)
+        if n == 0:
+            return []
+        chars = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz']
+        strs = [chars[int(d) - 2] for d in digits]
+        res = []
+        for s in strs:
+            if not res:
+                res = list(s)
+            else:
+                cache = []
+                for item in res:
+                    for letter in s:
+                        cache.append(item + letter)
+                res = cache
+        return res