https://leetcode.com/problems/first-unique-character-in-a-string/

s = "leetcode"
return 0.

s = "loveleetcode"
return 2.

음.. hash에 저장해 가면서 카운트 해주면 될 거 같다. 해보자.

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

Runtime: 56 ms, faster than 47.86% of C++ online submissions for First Unique Character in a String.

Memory Usage: 10.7 MB, less than 72.47% of C++ online submissions for First Unique Character in a String.