面试笔试杂项积累-leetcode 241-245

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242.242-Valid Anagram-Difficulty: Easy

Given two strings s and t, write a function to determine ift is an anagram of s.

For example,
s = "anagram", t = "nagaram", return true.
s = "rat", t = "car", return false.

Note:
You may assume the string contains only lowercase alphabets.

思路

查找t的字母是否全和s相同(数目也相同)

使用哈希表匹配轻松解决

要注意重复情况，在哈希的value几下当前字母个数，t遇到就-1，到0还有的话就是false了

public class Solution {    public bool IsAnagram(string s, string t) {          if (s.Length != t.Length)            return false;        Hashtable hash = new Hashtable();        for (int i = 0; i < s.Length; i++)        {            if (hash.ContainsKey(s[i]))                hash[s[i]] = (int)hash[s[i]] + 1;            else                hash.Add(s[i], 1);        }        for (int i = 0; i < s.Length; i++)        {            if (hash.ContainsKey(t[i]))            {                if ((int)hash[t[i]] <= 0)                    return false;                hash[t[i]] = (int)hash[t[i]] - 1;            }            else                return false;        }        return true;    }}

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