POJ3630

Posted 2021-01-18 shadowland

Tire树裸题，一开始写动态的字典树，然后TLE，每次new一个新节点耗费时间较多。后来改成数组模拟的。

//#include <bits/stdc++.h>
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std ; 
const int maxN = 10010 ; 

struct stringStruct {
    char str[ 20 ] ; 
    int len ; 
}ss[ maxN ] ; 

struct tireNode {
    int cnt ; 
    bool last ; 
    struct tireNode *next[ 10 ] ; 
    tireNode ( ) {
        cnt = 0 ; 
        last = false; 
        memset ( next , 0 , sizeof ( next ) ) ;
    }
};

bool cmp ( stringStruct a , stringStruct b ) {
    return a.len < b.len ; 
}

bool insert ( tireNode *root , char str[ ] ) {
    int len = strlen ( str ) ; 
    tireNode *cur = root ;
    
    for ( int i=0 ; i<len ; ++i ) {
        char ch = str[ i ] - ‘0‘ ; 
        if ( cur -> next[ ch ] == NULL ) {
            tireNode* newNode = new tireNode ; 
            cur -> next[ ch ] = newNode ; 
        } 
        if ( cur -> last ) return true ; 
        cur = cur -> next[ ch ] ;
        cur->cnt++ ; 
    }
    cur -> last = true ;
    return false ; 
}

int main ( ) {
    int T ; 
    for ( scanf( "%d" , &T ) ; T ; --T ) {
        tireNode* root = new tireNode ; 
        int N ; 
        scanf ( "%d
" , &N ) ;
        for ( int i=1 ; i<=N ; ++i ) {
            char ch = getchar ( ) ;
            int lenn = 0 ; 
            while ( ch != ‘
‘ ) {
                ss[ i ].str[ lenn++ ] = ch ; 
                ch = getchar ( ) ;
            }
            ss[ i ].len = lenn ; 
        } 
        sort ( ss + 1 , ss + N + 1 , cmp ) ; 
        bool flag = true ; 
        for ( int i=1 ; i<=N ; ++i ) {
            if ( insert ( root , ss[ i ].str ) ) {
                flag = false ; 
                break ; 
            }
        }
        if ( flag ) printf ( "YES
" ) ;
        else printf ( "NO
" ) ;
    }
    return 0 ; 
}

TLE动态字典树

#include <cstdio>
#include <algorithm>
#include <cstring>

using namespace std ; 
const int maxN = 100100 ;
typedef long long LL ; 

struct stringStruct {
    char str[ 20 ] ; 
    int len ; 
}ss[ maxN ] ; 

int trie[ maxN ][ 10 ] ; 
bool end[ maxN ] ; 
bool cmp ( stringStruct a , stringStruct b ) {
    return a.len < b.len ; 
}

int _cnt ;

bool insert ( char str[ ] ) {
    int cur = 1 , len = strlen ( str + 1 ) ;  
    for ( int i=1 ; i<=len ; ++i ) {
        int ch = str[ i ] - ‘0‘ ; 
        if ( !trie[ cur ][ ch ] ) 
            trie[ cur ][ ch ] = ++_cnt ; 
        if ( end[ cur ] ) return true ; 
        cur = trie[ cur ][ ch ] ; 
    }
    end[ cur ] = true ; 
    return false ; 
}

int main ( ) {
    int T , N ; 
    for ( scanf ( "%d" , &T ) ; T ; --T ) {
        memset ( trie , 0 , sizeof ( trie ) ) ;
        memset ( end , false , sizeof ( end ) ) ;
        _cnt = 1 ; 
        scanf ( "%d" , &N ) ; 
        for ( int i=1 ; i<=N ; ++i ) {
            scanf ( "%s" , ss[ i ].str + 1 ) ; 
            ss[ i ].len = strlen ( ss[ i ].str + 1 ) ;
        }
        sort ( ss + 1 , ss + N + 1 , cmp ) ; 
        bool flag = true ; 
        for ( int i=1 ; i<=N ; ++i ) {
            if ( insert ( ss[ i ].str ) ) {
                flag = false ; 
                break ; 
            } 
        }
        if ( flag )printf ( "YES
" ) ; 
        else printf ( "NO
" ) ; 
    }    
    return 0 ; 
}

AC数组模拟