Check if the key is composed of an arbitrary number of concatenations of strings from the dictionar-优快云博客

本文介绍了一种检查给定字符串是否能由字典中单词任意次拼接而成的有效算法。通过两种不同语言实现的方法，展示了如何高效判断目标字符串是否符合要求。适用于字符串处理和搜索场景。

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转自：http://www.careercup.com/question?id=5705581721550848

You're given a dictionary of strings, and a key. Check if the key is composed of an arbitrary number of concatenations of strings from the dictionary. For example:

dictionary: "world", "hello", "super", "hell"
key: "helloworld" --> return true
key: "superman" --> return false
key: "hellohello" --> return true

method1

import java.util.HashSet;

public class ConcantentationOfStrings {
	static String[] dic={"world","hello","super","hell"};


	static boolean isConcantentationOfOtherStrings(String word)
	{
		HashSet<String> hs=new HashSet<String>();
		
		for(String s: dic) hs.add(s);
		int len=word.length();

		boolean[] table=new boolean[len+1];	
		table[0]=true;	

		for(int i=0; i < len;i++)
		{
			for(int j=i; j >= 0;j--)
			{
				String subWord=word.substring(j,i+1);
				if(hs.contains(subWord))
				{
					if(table[j]) table[i+1]=true;
				}
			}
		}

		return table[len];
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println(isConcantentationOfOtherStrings("hellworld"));

	}

}

method2

class StringDictionary{
public:
    bool checkConcatenation(unordered_set<string>& dictionary, string str){
        if(str.length() == 0)   return true;
        for(int i = 1; i <= str.length(); i ++){
            string t = str.substr(0,i);
            if(dictionary.find(t)!= dictionary.end()){
                if(checkConcatenation(dictionary, str.substr(i))){
                    return true;
                }
            }
        }
        return false;
    }
};