171. Anagrams【medium】

Given an array of strings, return all groups of strings that are anagrams.

Notice

All inputs will be in lower-case

 

Example

Given ["lint", "intl", "inlt", "code"], return ["lint", "inlt", "intl"].

Given ["ab", "ba", "cd", "dc", "e"], return ["ab", "ba", "cd", "dc"].

Challenge

What is Anagram?
- Two strings are anagram if they can be the same after change the order of characters.

解法一：

class Solution {
public:    
    /**
     * @param strs: A list of strings
     * @return: A list of strings
     */
    string getSortedString(string &str) {
        static int count[26];
        for (int i = 0; i < 26; i++) {
            count[i] = 0;
        }
        for (int i = 0; i < str.length(); i++) {
            count[str[i] - 'a']++;
        }
        
        string sorted_str = "";
        for (int i = 0; i < 26; i++) {
            for (int j = 0; j < count[i]; j++) {
                sorted_str = sorted_str + (char)('a' + i);
            }
        }
        return sorted_str;
    }
    
    vector<string> anagrams(vector<string> &strs) {
        unordered_map<string, int> hash;
        
        for (int i = 0; i < strs.size(); i++) {
            string str = getSortedString(strs[i]);
            if (hash.find(str) == hash.end()) {
                hash[str] = 1;
            } else {
                hash[str] = hash[str] + 1;
            }
        }
        
        vector<string> result;
        for (int i = 0; i < strs.size(); i++) {
            string str = getSortedString(strs[i]);
            if (hash.find(str) == hash.end()) {
                continue;
            } else {
                if (hash[str] > 1) {
                    result.push_back(strs[i]);
                }
            }
        }
        return result;
    }
};

手动实现了字符串的排序，有些复杂，参考@NineChapter 的代码

解法二：

class Solution {
public:    
    /**
     * @param strs: A list of strings
     * @return: A list of strings
     */
    vector<string> anagrams(vector<string> &strs) {
        int size = strs.size(), i = 0;
        if (size <= 0) {
            return vector<string>();
        }

        vector<string> result;
        map<string, int> hash;
        for (i = 0; i < size; i++) {
            string temp = strs[i];
            sort(temp.begin(), temp.end());
            hash[temp]++;
        }
        for (i = 0; i < size; i++) {
            string temp = strs[i];
            sort(temp.begin(), temp.end());
            if (hash[temp] > 1) {
                result.push_back(strs[i]);
            }
        }
        return result;
    }
};

直接用STL的sort函数搞