Valid Anagram 比较两个字符串是否相同

Valid Anagram

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.

class Solution {
public:

//我觉得可以哈希做，消耗内存；也可以排序后按字比较，复杂度高一点
    bool isAnagram(string s, string t) {
       /* 
       //哈希做 AC
        char str[256];
        int len1=s.size(),len2=t.size();
        if(len1!=len2)
            return false;
        else if(len1==0)
            return true;
        int i;
        memset(str,0,sizeof(str));
        for(i=0;i<len1;i++)
        {
            str[s[i]]++;
        }
        for(i=0;i<len2;i++)
        {
            str[t[i]]--;
        }
        for(i=97;i<=122;i++)
        {
            if(str[i]!=0)
                break;
        }
        if(i!=123)
            return false;
        else
            return true;
            
      */
      
     int i,len1=s.size(),len2=t.size();
     if(len1!=len2)
        return false;
     else if(len1==0)
        return true;
     sort(s.begin(),s.end());
     sort(t.begin(),t.end());
     for(i=0;i<len1;i++)
     {
         if(s[i]!=t[i])
            break;
     }
     if(i==len1)
        return true;
     else
        return false;
    }
};