387. First Unique Character in a String

哈希表求解

class Solution {
public:
    int firstUniqChar(string s) {
        unordered_map<char,int> table;
        for(int i=0;i<s.size();i++)
        {
            if(table.find(s[i])!=table.end()) //find 
            {
                table[s[i]]=-1;
            }
            else
                table[s[i]]=i;
        }
        for(int i=0;i<s.size();i++)
        {
            if(table[s[i]]>=0)
                return table[s[i]];
        }
        return -1;
    }
};