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# 題目敘述
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
# 解題思路
# Solution
import java.util.HashMap; | |
import java.util.Map; | |
class Solution { | |
public int firstUniqChar(String s) { | |
Map<Character, Integer> map = new HashMap<>(); | |
for(int i = 0; i < s.length(); i++){ | |
map.put(s.charAt(i), map.getOrDefault(s.charAt(i), 0) + 1); | |
} | |
for(int i = 0; i < s.length(); i++){ | |
if(map.get(s.charAt(i)) == 1){ | |
return i; | |
} | |
} | |
return -1; | |
} | |
} |
單字
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片語 & 搭配詞
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