refactor: remove Java code sections from all LeetCode Hot 100 markdown files

- Remove all "## Java 解法" sections and Java code blocks
- Replace "## Go 解法" with "## 解法"
- Remove "### Go 代码要点" and "### Java 代码要点" sections
- Keep all Go code sections intact
- Maintain complete documentation structure and content
- Update 22 markdown files in the LeetCode Hot 100 directory

16-LeetCode Hot 100/电话号码的字母组合.md

@@ -153,84 +153,6 @@ func main() {
 
 ### Java 实现（回溯法）
 
-```java
-import java.util.ArrayList;
-import java.util.List;
-
-public class LetterCombinations {
-
-    public List<String> letterCombinations(String digits) {
-        List<String> result = new ArrayList<>();
-        if (digits == null || digits.length() == 0) {
-            return result;
-        }
-
-        // 数字到字母的映射
-        String[] phoneMap = {
-            "",     // 0
-            "",     // 1
-            "abc",  // 2
-            "def",  // 3
-            "ghi",  // 4
-            "jkl",  // 5
-            "mno",  // 6
-            "pqrs", // 7
-            "tuv",  // 8
-            "wxyz"  // 9
-        };
-
-        StringBuilder current = new StringBuilder();
-        backtrack(digits, 0, phoneMap, current, result);
-        return result;
-    }
-
-    private void backtrack(String digits, int index, String[] phoneMap,
-                          StringBuilder current, List<String> result) {
-        if (index == digits.length()) {
-            result.add(current.toString());
-            return;
-        }
-
-        // 获取当前数字对应的所有字母
-        int digit = digits.charAt(index) - '0';
-        String letters = phoneMap[digit];
-
-        for (int i = 0; i < letters.length(); i++) {
-            // 选择当前字母
-            current.append(letters.charAt(i));
-            // 递归处理下一个数字
-            backtrack(digits, index + 1, phoneMap, current, result);
-            // 撤销选择（回溯）
-            current.deleteCharAt(current.length() - 1);
-        }
-    }
-
-    // 测试用例
-    public static void main(String[] args) {
-        LetterCombinations solution = new LetterCombinations();
-
-        // 测试用例1
-        String digits1 = "23";
-        System.out.println("输入: " + digits1);
-        System.out.println("输出: " + solution.letterCombinations(digits1));
-
-        // 测试用例2
-        String digits2 = "";
-        System.out.println("\n输入: " + digits2);
-        System.out.println("输出: " + solution.letterCombinations(digits2));
-
-        // 测试用例3
-        String digits3 = "2";
-        System.out.println("\n输入: " + digits3);
-        System.out.println("输出: " + solution.letterCombinations(digits3));
-
-        // 测试用例4: 最长输入
-        String digits4 = "9999";
-        System.out.println("\n输入: " + digits4);
-        System.out.println("输出长度: " + solution.letterCombinations(digits4).size());
-    }
-}
-```
 
 ### Go 实现（队列迭代法）
 
@@ -275,39 +197,6 @@ func letterCombinationsIterative(digits string) []string {
 
 ### Java 实现（队列迭代法）
 
-```java
-public List<String> letterCombinationsIterative(String digits) {
-    List<String> result = new ArrayList<>();
-    if (digits == null || digits.length() == 0) {
-        return result;
-    }
-
-    String[] phoneMap = {
-        "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"
-    };
-
-    // 初始化队列
-    List<String> queue = new ArrayList<>();
-    queue.add("");
-
-    for (int i = 0; i < digits.length(); i++) {
-        int digit = digits.charAt(i) - '0';
-        String letters = phoneMap[digit];
-        List<String> newQueue = new ArrayList<>();
-
-        // 取出队列中所有组合，与当前字母组合
-        for (String combination : queue) {
-            for (int j = 0; j < letters.length(); j++) {
-                newQueue.add(combination + letters.charAt(j));
-            }
-        }
-
-        queue = newQueue;
-    }
-
-    return queue;
-}
-```
 
 ## 复杂度分析