Classic 150 Interview Questions P242 Valid Anagram

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Timeline

Timeline

2025-11-13

init

Hash table

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Problem:

P242 Valid Anagram

https://leetcode.cn/problems/valid-anagram/description/?envType=study-plan-v2&envId=top-interview-150

Use a hash table to record the count of each letter, then tally.

#include <string>
#include <unordered_map>
using std::string;
using std::unordered_map;

class Solution {
    public:
	bool isAnagram(string s, string t)
	{
		if (s.size() != t.size()) return false;
		
		unordered_map<char, int> smap;
		
		for (char &ch : s)
			smap[ch]++;

		for (char &ch : t) {
			if (!smap.count(ch))
				return false;

			smap[ch]--;
			
			if (smap[ch] < 0)
				return false;
		}
		return true;
	}
};