Update kama54.替换数字.md

修改kama54.替换数字中的java实例代码思路流程，与为C++代码保持一致

problems/kama54.替换数字.md

@@ -146,17 +146,42 @@ for (int i = 0; i < a.size(); i++) {
 ```java
 import java.util.Scanner;
 
-class Main {
-    public static void main(String[] args) {
-        Scanner in = new Scanner(System.in);
-        String s = in.nextLine();
-        StringBuilder sb = new StringBuilder();
+public class Main {
+    
+    public static String replaceNumber(String s) {
+        int count = 0; // 统计数字的个数
+        int sOldSize = s.length();
         for (int i = 0; i < s.length(); i++) {
             if(Character.isDigit(s.charAt(i))){
-                sb.append("number");
-            }else sb.append(s.charAt(i));
+                count++;
             }
-        System.out.println(sb);
+        }
+        // 扩充字符串s的大小，也就是每个空格替换成"number"之后的大小
+        char[] newS = new char[s.length() + count * 5];
+        int sNewSize = newS.length;
+        // 将旧字符串的内容填入新数组
+        System.arraycopy(s.toCharArray(), 0, newS, 0, sOldSize);
+        // 从后先前将空格替换为"number"
+        for (int i = sNewSize - 1, j = sOldSize - 1; j < i; j--, i--) {
+            if (!Character.isDigit(newS[j])) {
+                newS[i] = newS[j];
+            } else {
+                newS[i] = 'r';
+                newS[i - 1] = 'e';
+                newS[i - 2] = 'b';
+                newS[i - 3] = 'm';
+                newS[i - 4] = 'u';
+                newS[i - 5] = 'n';
+                i -= 5;
+            }
+        }
+        return new String(newS);
+    };
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        String s = scanner.next();
+        System.out.println(replaceNumber(s));
+        scanner.close();
     }
 }
 ```