Leetcode题目：Valid Anagram

题目：

Given two strings s and t, write a function to determine if t is an anagram of s.

For example,
s = "anagram", t = "nagaram", return true.
s = "rat", t = "car", return false.

Note:
You may assume the string contains only lowercase alphabets

Follow up:
What if the inputs contain unicode characters? How would you adapt your solution to such case?

解答思路：

设置一个大小为26的整整型数组来记录s这个字符串中每个字母出现的次数，判断t字符串中每个字母出现的次数是否与之相同，若相同，则说明构成变位词。

代码如下：

class Solution {
public:
    bool isAnagram(string s, string t) {
        int s_size = s.length();
        int t_size = t.length();
        if(s_size != t_size)
        {
            return false;
        }
        if(s_size == 0)
            return true;
        char s_copy[s_size + 1];
        char t_copy[t_size + 1];
        strncpy(s_copy,s.c_str(),s_size);
        strncpy(t_copy,t.c_str(),t_size);
        int num[26]={0};
        for(int i = 0;i < s_size;i++)
        {
            num[s_copy[i]-‘a‘]++;
        }
        for(int i = 0;i < t_size;i++)
        {
            num[t_copy[i]-‘a‘]--;
            if(num[t_copy[i]-‘a‘] < 0)
                return false;
        }
        for(int i = 0;i < 26;i++)
        {
            if(num[i] != 0)
                return false;
        }
        return true;
    }
};