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[leetcode] problem 387 – first unique character in a string

admin 11月 13, 2020 0

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

Examples

No.1

s = “leetcode”
return 0.

No.2

s = “loveleetcode”,
return 2.

Note

You may assume the string contain only lowercase letters.

Code

public int (String s) {
    if (s == null || s.length() < 1)
        return -1;

    int[] index = new int[26];

    for (int i = 0; i < s.length(); i++) {
        int idx = s.charAt(i) - 'a';
        index[idx]++;
    }

    for (int i = 0; i < s.length(); i++) {
        int idx = s.charAt(i) - 'a';

        if (index[idx] == 1)
            return i;
    }

    return -1;
}