389. Find the Difference

最新推荐文章于 2024-09-29 07:15:00 发布

jmspan

最新推荐文章于 2024-09-29 07:15:00 发布

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分类专栏：直方图频率统计文章标签： leetcode

本文链接：https://blog.youkuaiyun.com/jmspan/article/details/52940790

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频率统计

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本文介绍了一种通过直方图频率统计的方法来找出一个字符串相对于另一个字符串新增加的一个字母。该方法通过比较两个字符串中各字符出现的频率，找出唯一频率不同的字符。

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原题网址：https://leetcode.com/problems/find-the-difference/

Given two strings s and t which consist of only lowercase letters.

String t is generated by random shuffling string s and then add one more letter at a random position.

Find the letter that was added in t.

Example:

Input:
s = "abcd"
t = "abcde"

Output:
e

Explanation:
'e' is the letter that was added.

方法：直方图频率统计。

public class Solution {
    private int[] frequency(String s) {
        int[] f = new int[26];
        char[] sa = s.toCharArray();
        for(char c : sa) {
            f[c - 'a'] ++;
        }
        return f;
    }
    public char findTheDifference(String s, String t) {
        int[] fs = frequency(s);
        int[] ft = frequency(t);
        for(int i = 0; i < fs.length; i++) {
            if (fs[i] != ft[i]) {
                return (char)('a' + i);
            }
        }
        return (char)0;
    }
}