387. First Unique Character in a String

Problem

leetcode 바로가기

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

Constraints:

• 1 <= s.length <= 105
• s consists of only lowercase English letters.

Solution

/**
 * @param {string} s
 * @return {number}
 */
var firstUniqChar = function(s) {
  let obj = {};
    let r;

    // obj[s[0]] = 1;
    for(let i = 0; i < s.length; i++) {
      obj[s[i]] == undefined ? obj[s[i]] = 1 : obj[s[i]] += 1;
    }
    
    for(let [key, value] of Object.entries(obj)) {
      if (value == 1) {
        r = key;
        break;
      }
  }
  
  return s.indexOf(r);