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  • LeetCode_387. First Unique Character in a String

    387. First Unique Character in a String

    Easy

    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.
    

    Note: You may assume the string contain only lowercase letters.

    package leetcode.easy;
    
    public class FirstUniqueCharacterInAString {
    	public int firstUniqChar(String s) {
    		java.util.HashMap<Character, Integer> count = new java.util.HashMap<Character, Integer>();
    		int n = s.length();
    		// build hash map : character and how often it appears
    		for (int i = 0; i < n; i++) {
    			char c = s.charAt(i);
    			count.put(c, count.getOrDefault(c, 0) + 1);
    		}
    
    		// find the index
    		for (int i = 0; i < n; i++) {
    			if (count.get(s.charAt(i)) == 1)
    				return i;
    		}
    		return -1;
    	}
    
    	@org.junit.Test
    	public void test() {
    		System.out.println(firstUniqChar("leetcode"));
    		System.out.println(firstUniqChar("loveleetcode"));
    	}
    }
    
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  • 原文地址:https://www.cnblogs.com/denggelin/p/11875310.html
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