使用Trie对字符串(或单词)进行排序

给定一个字符串数组，请按字母(字典)顺序打印它们。如果输入数组中有重复项，则只需要打印一次即可。

例子：

Input : "abc", "xy", "bcd"
Output : abc bcd xy         

Input : "geeks", "for", "geeks", "a", "portal", 
        "to", "learn", "can", "be", "computer", 
        "science", "zoom", "yup", "fire", "in", "data"
Output : a be can computer data fire for geeks
         in learn portal science to yup zoom

Trie是一种有效的数据结构，用于存储字符串的数据。要按字母顺序打印字符串，我们必须首先插入trie，然后执行预遍历以按字母顺序打印。

// C++ program to sort an array of strings
// using Trie
#include 
using namespace std;
  
const int MAX_CHAR = 26;
  
struct Trie {
  
    // index is set when node is a leaf
    // node, otherwise -1;
    int index;
  
    Trie* child[MAX_CHAR];
  
    /*to make new trie*/
    Trie()
    {
        for (int i = 0; i < MAX_CHAR; i++)
            child[i] = NULL;
        index = -1;
    }
};
  
/* function to insert in trie */
void insert(Trie* root, string str, int index)
{
    Trie* node = root;
  
    for (int i = 0; i < str.size(); i++) {
  
        /* taking ascii value to find index of
          child node */
        char ind = str[i] - 'a';
  
        /* making new path if not already */
        if (!node->child[ind])
            node->child[ind] = new Trie();
  
        // go to next node
        node = node->child[ind];
    }
  
    // Mark leaf (end of word) and store
    // index of word in arr[]
    node->index = index;
}
  
/* function for preorder traversal */
bool preorder(Trie* node, string arr[])
{
    if (node == NULL)
        return false;
  
    for (int i = 0; i < MAX_CHAR; i++) {
        if (node->child[i] != NULL) {
  
            /* if leaf node then print key*/
            if (node->child[i]->index != -1)
                cout << arr[node->child[i]->index] << endl;
  
            preorder(node->child[i], arr);
        }
    }
}
  
void printSorted(string arr[], int n)
{
    Trie* root = new Trie();
  
    // insert all keys of dictionary into trie
    for (int i = 0; i < n; i++)
        insert(root, arr[i], i);
  
    // print keys in lexicographic order
    preorder(root, arr);
}
  
// Driver code
int main()
{
    string arr[] = { "abc", "xy", "bcd" };
    int n = sizeof(arr) / sizeof(arr[0]);
    printSorted(arr, n);
    return 0;
}

输出：

abc bcd xy