ZOJ1166

ZOJ1166-Anagram Checker

算法分析：

一、数据结构

二、数据读取与预处理

1.读取字典（无需排序）

2,.读取短语（要排序）

三、统计每个字母出现次数

构造变位词时，只关注有哪些字母，以及字母频数。统计结果存放在数组中。

四、采用回溯算法，构造变位词

1.判断短语中字母是否构造完毕

2.使用回溯算法，构造变位词短语

ps:对字典剪枝优化，若被测试字符串不包含字典中某条目，则该条目可被剪枝，加速搜索过程。

#include #include #include #include #include using namespace std;/**dictionary words**/string word[2000];/**Word in phrase**/string sword[20];/**phrase sorted in alphabetic order**/string phrase;string oldphrase;/**Number of dictionary words, number of words in phrase.**/int n=0, m;/**Count of letters in phrase.**/int cont[26];void findAnagram(int idx, vector &v){     bool find=true;     for (int i=0; i<26; i++)      {       if (cont[i] > 0)        { find = false;  break; }     }     if (find)     {        string s;        for (int i=0; i 0) s += " ";            s += v[i];        }        if (s != phrase) cout<>word[n], word[n] != "#") n++;    string s;    sort(word, word+n);    m=0;    while (1)    {          cin>>sword[m];          if ("#" == sword[m++]) break;          if (cin.get() == '/n')          {          /**          Keep the old phrase for output.          **/             oldphrase = "";             for (int i=0; i v;             findAnagram(0, v);             m = 0;          }    }}

#include  #include  #include  #include  #include  #include    using namespace std;    namespace  {      set words;      int src[26];      vector dict;      string line;      vector stack;        bool match(const string &s)      {          int temp[26];          memset(temp, 0, sizeof(temp));          for (size_t i = 0; i < s.size(); i++)              temp[s[i] - 'A']++;          for (int i = 0; i < 26; i++)              if (temp[i] && temp[i] > src[i])                  return false;          return true;      }        void forward(const string &s)      {          for (size_t i = 0; i < s.size(); i++)              src[s[i] - 'A']--;      }        void back(const string &s)      {          for (size_t i = 0; i < s.size(); i++)              src[s[i] - 'A']++;      }        bool find()      {          for (int i = 0; i < 26; i++)              if (src[i])                  return false;          return true;      }        void dfs()      {          if (find())          {              cout << line << " =";              for (size_t i = 0; i < stack.size(); i++)                  cout << " " << stack[i];              cout << endl;              return;          }            for (size_t i = 0; i < dict.size(); i++)              if (stack.empty() || (!stack.empty() && dict[i] > stack.back()))                  if (words.find(dict[i]) == words.end() && match(dict[i]))                  {                      forward(dict[i]);                      stack.push_back(dict[i]);                      dfs();                      stack.pop_back();                      back(dict[i]);                  }      }  }    int main()  {      string word;      while (cin >> word, word != "#")          dict.push_back(word);      cin >> ws;      while (getline(cin, line), line != "#")      {          words.clear();          istringstream ism(line);          while (ism >> word)              words.insert(word);          memset(src, 0, sizeof(src));          for (size_t i = 0; i < line.size(); i++)              if (line[i] >= 'A' && line[i] <= 'Z')                  src[line[i] - 'A']++;            stack.clear();          dfs();      }      return 0;  }