First Unique Character In A String Problem
Description
LeetCode Problem 387.
Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1.
Example 1:
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Input: s = "leetcode"
Output: 0
Example 2:
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Input: s = "loveleetcode"
Output: 2
Example 3:
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Input: s = "aabb"
Output: -1
Constraints:
- 1 <= s.length <= 10^5
- s consists of only lowercase English letters.
Sample C++ Code
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class Solution {
public:
int firstUniqChar(string s) {
int ht[26] = {0};
for (int i = 0; i < s.size(); i ++) {
ht[s[i] - 'a'] ++;
}
for (int i = 0; i < s.size(); i ++) {
if (ht[s[i] - 'a'] == 1)
return i;
}
return -1;
}
};