LeetCode-First Unique Character in a String
阿新 • • 發佈:2018-12-12
Description: 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.
題意:給定一個字串,返回字串中第一個在字串中只出現過一次的字元的下標位置,沒有找到就返回-1;
解法:我們可以利用雜湊表,遍歷字串,將字元及其出現的次數作為鍵值對儲存在表中;之後,再從首部開始遍歷字串,返回對應鍵的值1的那個字元的下標位置;
Java
class Solution { public int firstUniqChar(String s) { Map<Character, Integer> table = new HashMap<>(); for (int i = 0; i < s.length(); i++) { table.put(s.charAt(i), table.getOrDefault(s.charAt(i), 0) + 1); } for (int i = 0; i < s.length(); i++) { if (table.get(s.charAt(i)) == 1) { return i; } } return -1; } }