242有效的字母异位词 349. 两个数组的交集 202快乐数

这几道都比较简单，主要是熟悉哈希的操作

class Solution {
public:
    bool isAnagram(string s, string t) {
        int alphab[26] = {0};

        for(int i=0; i < s.size(); i++)
        {
            alphab[ s[i] - 'a' ]++;
        }

        for( int i=0; i<t.size(); i++)
        {
            alphab[ t[i] - 'a' ]--;
        }

        for(int i=0; i<26; i++)
        {
            if( alphab[i] !=0 )
                return false;
        }

        return true;
    }
};

class Solution {
public:
    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
        unordered_set<int> set1;
        unordered_set<int> result1;
        for(int i=0 ;i < nums1.size(); i++)
        {
            set1.insert(nums1[i]);
        }
        for(int i = 0; i<nums2.size(); i++)
        {
            if( set1.find(nums2[i]) != set1.end() )
                result1.insert(nums2[i]);
        }
        return vector<int>(result1.begin(), result1.end() );
    }
};

class Solution {
public:
    int getsum(int n)
    {
        int sum=0;
        while(n)
        {
            sum += (n%10) * (n%10);
            n = n/10;
        }
        return sum;
    }

    bool isHappy(int n) {
        unordered_set<int> set1 {0};
        int result = 0;
        while(1)
        {
            result = getsum(n);
            n = result;
            if( result == 1 )
                return true;

            if( set1.find(result) !=set1.end() )
                return false;
            else
                set1.insert(result); 
        }
    }
};