剑指 Offer 50. 第一个只出现一次的字符
class Solution {
public char firstUniqChar(String s) {
Map<Character, Boolean> map = new LinkedHashMap<>();
for (char c : s.toCharArray()) {
map.put(c, !map.containsKey(c));
}
for (char c : map.keySet()) {
if (map.get(c) == true)
return c;
}
return ' ';
}
}