UVA 10391 Compound Words

You are to find all the two-word compound words in a dictionary. A two-word compound word is a word in the dictionary that is theconcatenation of exactly two other words in the dictionary.

Input

Standard input consists of a number of lowercase words, one per line,in alphabetical order. There will be no more than 120,000 words.

Output

Your output should contain all the compound words, one per line, inalphabetical order.

Sample Input

a
alien
born
less
lien
never
nevertheless
new
newborn
the
zebra

Sample Output

alien
newborn

思路：

两种思路，合成和拆分。前者时间复杂度为O(n^2),超时。后者的为O(n*m),m小于n，VJ50ms，AC。

#include <iostream>
#include <cstdlib>
#include <string>
#include <map>

using namespace std;

const int maxn=120000+5;

int main()
{
    string word[maxn];
    map<string,bool> jud;
    int cnt=0;
    while(cin>>word[cnt])
        jud[word[cnt++]]=true;

    for(int i=0;i<cnt;i++)
    for(int j=0;j<(int)word[i].size()-1;j++)
    {
        string a=word[i].substr(0,j+1);
        if(!jud[a]) continue;
        string b=word[i].substr(j+1);
        if(!jud[b]) continue;
        cout<<word[i]<<endl;
        break;
    }
    return 0;
}