UVa 10391 - Compound Words 字符串hash

Problem E: 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 the concatenation 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, in alphabetical order.

Sample Input

a
alien
born
less
lien
never
nevertheless
new
newborn
the
zebra

Sample Output

alien
newborn

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#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>

using namespace std;

const int maxn=32111;
const int maxm=11000019;

int head[maxm];
int next[maxm];
char word[maxn][30];

int hash(char *p,int prime=10000019)
{
    unsigned int h=0,g;
    for (;*p;++p){
        h=(h<<4)+*p;
        if (g=h&0xf0000000){
            h=h^(g>>24);
            h=h^g;
        }
    }
    return h%prime;
}

void addhash(int s)
{
    int h=hash(word[s]);
    next[s]=head[h];
    head[h]=s;
}

bool searchstr(char* str)
{
    int h=hash(str);
    for (int i=head[h];i!=-1;i=next[i])
    {
        if (strcmp(str,word[i])==0) return true;
    }
    return false;
}

int main()
{
    char str[30];
    int n=1;
    memset(head,-1,sizeof(head));
    while (gets(word[n]))
    {
        addhash(n);
        n++;
    }
    for (int i=1;i<n;i++)
    {
        for (int j=1;j<strlen(word[i]);j++)
        {
            strcpy(str,word[i]);
            str[j]='\0';
            if (searchstr(str)&&searchstr(word[i]+j))
            {
                puts(word[i]);
                break;
            }
        }
    }
    return 0;
}