1.     /**
    2.      * 14、最长公共前缀
    3.      *
    4.      * @param strs
    5.      * @return
    6.      */
    7.     public static String longestCommonPrefix(String[] strs) {
    8.         if (strs.length == 0) {
    9.             return "";
    10.         }
    11.         if (strs.length == 1) {
    12.             return strs[0];
    13.         }
    14.         // 先找出一个数组内最小字符串下标
    15.         int minStrIndex = 0;
    16.         for (int i = 0; i < strs.length; i++) {
    17.             if (strs[i].length() < strs[minStrIndex].length()) {
    18.                 minStrIndex = i;
    19.             }
    20.         }
    21.         String compareString = strs[minStrIndex];
    22.         for (String str : strs) {
    23.             while (!str.startsWith(compareString)) {
    24.                 // 不匹配减一重新匹配
    25.                 compareString = compareString.substring(0, compareString.length() - 1);
    26.             }
    27.         }
    28.         return compareString;
    29.     }
    31.     /**
    32.      * 9、回文数
    33.      *
    34.      * @param x
    35.      * @return
    36.      */
    37.     public static boolean isPalindrome(int x) {
    38.         if (x < 0) {
    39.             return false;
    40.         }
    41.         char[] xChars = String.valueOf(x).toCharArray();
    42.         for (int i = 0; i < (xChars.length / 2); i++) {
    43.             if (xChars[i] != xChars[xChars.length - 1 - i]) {
    44.                 return false;
    45.             }
    46.         }
    47.         return true;
    48.     }
    50.     /**
    51.      * 7、整数反转
    52.      *
    53.      * @param x
    54.      * @return
    55.      */
    56.     public static int reverse(int x) {
    57.         String xString = String.valueOf(x);
    58.         if (xString.length() == 0) {
    59.             return 0;
    60.         }
    61.         if (xString.length() == 1) {
    62.             return x;
    63.         }
    64.         try {
    65.             if ("-".equals(xString.substring(0, 1))) {
    66.                 //负数
    67.                 String sign = xString.substring(0, 1);
    68.                 String other = xString.substring(1);
    69.                 char[] otherChars = other.toCharArray();
    70.                 StringBuilder newOther = new StringBuilder();
    71.                 for (int i = otherChars.length - 1; i >= 0; i--) {
    72.                     newOther.append(otherChars[i]);
    73.                 }
    74.                 return Integer.parseInt(sign + newOther.toString());
    75.             } else {
    76.                 //整数
    77.                 char[] otherChars = xString.toCharArray();
    78.                 StringBuilder newOther = new StringBuilder();
    79.                 for (int i = otherChars.length - 1; i >= 0; i--) {
    80.                     newOther.append(otherChars[i]);
    81.                 }
    82.                 return Integer.parseInt(newOther.toString());
    83.             }
    84.         } catch (Exception e) {
    85.             return 0;
    86.         }
    87.     }