Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.

Examples:

s = "leetcode"
return 0.

s = "loveleetcode",
return 2.

给定一个字符串，查找其中的第一个非重复字符并返回其索引。如果它不存在，返回-1。

例子:

s =“leetcode”
返回0。

s =“loveleetcode”,
返回2。

class Solution {
public int firstUniqChar(String s) {
int result = -1;
HashMap hm1 = new HashMap();
for (char c : s.toCharArray()) {
if (hm1.containsKey(c)) {
hm1.put(c, hm1.get(c) + 1);
} else {
hm1.put(c, 1);
}
}
for (int count = 0; count < s.length(); count++) {
if (hm1.get(s.charAt(count)) == 1) {
result = count;
break;
}
}
return result;
}
}