1. public static class Node2 {
    2.     public int pass;
    3.     public int end;
    4.     public HashMap<Integer, Node2> nexts;
    6.     public Node2() {
    7.         pass = 0;
    8.         end = 0;
    9.         nexts = new HashMap<>();
    10.     }
    11. }
    13. public static class Trie2 {
    14.     private Node2 root;
    16.     public Trie2() {
    17.         root = new Node2();
    18.     }
    20.     public void insert(String word) {
    21.         if (word == null) {
    22.             return;
    23.         }
    24.         char[] chs = word.toCharArray();
    25.         Node2 node = root;
    26.         node.pass++;
    27.         int index = 0;
    28.         for (int i = 0; i < chs.length; i++) {
    29.             index = (int) chs[i];
    30.             if (!node.nexts.containsKey(index)) {
    31.                 node.nexts.put(index, new Node2());
    32.             }
    33.             node = node.nexts.get(index);
    34.             node.pass++;
    35.         }
    36.         node.end++;
    37.     }
    39.     public void delete(String word) {
    40.         if (search(word) != 0) {
    41.             char[] chs = word.toCharArray();
    42.             Node2 node = root;
    43.             node.pass--;
    44.             int index = 0;
    45.             for (int i = 0; i < chs.length; i++) {
    46.                 index = (int) chs[i];
    47.                 if (--node.nexts.get(index).pass == 0) {
    48.                     node.nexts.remove(index);
    49.                     return;
    50.                 }
    51.                 node = node.nexts.get(index);
    52.             }
    53.             node.end--;
    54.         }
    55.     }
    57.     // word这个单词之前加入过几次
    58.     public int search(String word) {
    59.         if (word == null) {
    60.             return 0;
    61.         }
    62.         char[] chs = word.toCharArray();
    63.         Node2 node = root;
    64.         int index = 0;
    65.         for (int i = 0; i < chs.length; i++) {
    66.             index = (int) chs[i];
    67.             if (!node.nexts.containsKey(index)) {
    68.                 return 0;
    69.             }
    70.             node = node.nexts.get(index);
    71.         }
    72.         return node.end;
    73.     }
    75.     // 所有加入的字符串中，有几个是以pre这个字符串作为前缀的
    76.     public int prefixNumber(String pre) {
    77.         if (pre == null) {
    78.             return 0;
    79.         }
    80.         char[] chs = pre.toCharArray();
    81.         Node2 node = root;
    82.         int index = 0;
    83.         for (int i = 0; i < chs.length; i++) {
    84.             index = (int) chs[i];
    85.             if (!node.nexts.containsKey(index)) {
    86.                 return 0;
    87.             }
    88.             node = node.nexts.get(index);
    89.         }
    90.         return node.pass;
    91.     }
    92. }