Trie树算法实现(c++版)

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Trie树详解
代码如下:

//
// Created by Administrator on 2020/2/18.
//
#include 
#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;
typedef struct TrieNode{
    char c;
    int occurances;
    map<char,TrieNode*> children;
} *lpTnode,TNode;

vector<string> split(const string& str, const string& dlim){
    vector<string> res;
    if(str.empty()) return res;
    char *strs = new char[str.length()+1]; // 先将string转为char* 类型
    strcpy(strs,str.c_str());
    char *d = new char[dlim.length()+1];
    strcpy(d,dlim.c_str());
    char *p = strtok(strs,d);// 后面改成find&substr组合
    while (p){
        string sp = p;
        res.push_back(sp);
        p=strtok(nullptr,d);
    }
    return res;
}

class TrieTree {
    lpTnode root;
    int size;//字符串数量;
public:
    TrieTree();
    int insert(const string& str);
    bool remove(const string& str);
    bool contains(const string& str);
    int frequency(const string& str);
    int getSize(){
        return this->size;
    }
};

TrieTree::TrieTree() {
    this->root = new TNode;
    root->c = '\0';
    root->occurances = 0;
    this->size = 0;
}
int TrieTree::insert(const string& str) {
    if(str.length()<=0) {
        cout << "string is null" << endl;
        return 0;
    }
    int strLen = str.length();
    lpTnode atr = root;
    int i;
    for(i=0;i<strLen;i++){//每一个字符
        if(atr->children.find(str[i])!=atr->children.end()){
            atr = atr->children.at(str[i]);
        } else {//没有 则建立节点
            auto tn = new TNode;
            tn->c = str[i];
            tn->occurances =0;
            atr->children[str[i]] = tn;
            atr = atr->children[str[i]];
        }
    }
    atr->occurances++;// 无论是找到还是插入 最后一个字符都++;
    if(atr->occurances==1) this->size++;
    return 1;
}
bool TrieTree::remove(const string &str) {
    if(str.length()<=0) {
        cout << "string is null" << endl;
        return false;
    }
    int strLen = str.length();
    lpTnode atr = root;
    int i;
    for(i=0;i<strLen;i++){//每一个字符
        if(atr->children.find(str[i])!=atr->children.end()){
            atr = atr->children.at(str[i]);
        } else {//没有存在的字符；atr.children 为空了即树找完了但字符串还没完
            return false;
        }
    }
    // 如果完整运行到这:一是有这个字符串，二是有以该字符串为前缀的字符串
    bool residue = atr->occurances > 0; // 简化表达式
    if(residue) {
        atr->occurances--;
        this->size--;
        return true;
    }
    return false;
}

bool TrieTree::contains(const string &str) {
    if(str.length()<=0) {
        cout << "string is null" << endl;
        return false;
    }
    int strLen = str.length();
    lpTnode atr = root;
    int i;
    for(i=0;i<strLen;i++){//每一个字符
        if(atr->children.find(str[i])!=atr->children.end()){
            atr = atr->children.at(str[i]);
        } else {//没包含字符
            return false;
        }
    }
    return atr->occurances > 0; // 简化表达式
}

int TrieTree::frequency(const string &str) {
    if(str.length()<=0) {
        cout << "string is null" << endl;
        return 0;
    }
    int strLen = str.length();
    lpTnode atr = root;
    int i;
    for(i=0;i<strLen;i++){//每一个字符
        if(atr->children.find(str[i])!=atr->children.end()){
            atr = atr->children.at(str[i]);
        } else {//没包含字符
            return 0;
        }
    }
    return atr->occurances; // 简化表达式
}

int main(){
    ifstream infile;
    TrieTree tt;
    string buffer;
    string delimiter = " ";
    string fileName = R"(D:\hiicy\tempDownload\bible.txt)";
    infile.open(fileName,ios::in);// 读取文件
    while (!infile.eof()){
        getline(infile,buffer);
        vector<string> words = split(buffer,delimiter);
        for(auto const& word: words){
            tt.insert(word);
        }
    }
    int size = tt.getSize();
    cout<<"这个trie树共有: "<<size<<" 种不同单词"<<endl;
    string words[] = {"and","And","no","my","you","the"};
    for(auto const&word:words){
        int freq = tt.frequency(word);
        cout<<word<<endl<<
        "出现次数为"<<freq<<"次"<<endl;
    }
    cout<<tt.contains("die")<<endl;

    tt.remove("and");
    cout<<"and: "<<tt.frequency("and")<<endl;
    tt.remove("the");
    cout<<"the: "<<tt.frequency("the")<<endl;
    tt.remove("no");
    cout<<"no: "<<tt.frequency("no")<<endl;

    return 0;
}
}