Programming
Leetcode-387. First Unique Character in a String
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:
Input: s = "leetcode"
Output: 0
Example 2:
Input: s = "loveleetcode"
Output: 2
Example 3:
Input: s = "aabb"
Output: -1
<解題>
- 像是之前做過和String算頻率的題目類似，所以可以先計算各個字母出現的頻率
- 在一個迴圈從頭開始算頻率為1的字母
public class Solution {
public int firstUniqChar(String s) {
int freq [] = new int[26];
for(int i = 0; i < s.length(); i ++)
freq [s.charAt(i) - 'a'] ++;
for(int i = 0; i < s.length(); i ++)
if(freq [s.charAt(i) - 'a'] == 1)
return i;
return -1;
}
}