寫TOJ-29時遇到指標與參照的RE...

jd3

我真的不知道為什麼只要動到nxt就會RE啊啊啊啊啊連判斷式都死掉...
RE的地方 : " if(nxt == NULL) "
(旁邊有驚嘆號的地方)

[C++] 純文本查看 復制代碼

#include<iostream>
#include<cstdio>
#include<queue>


using namespace std;


struct Trie
{
        int contain;
        int number;
        Trie* next[26];
        Trie* fail;
        Trie* pre;
        
        Trie(){
                for(int i = 0 ; i < 26 ; i++)
                        next[i] = NULL;
        };
        Trie(int n , Trie *p){
                number = n;
                contain = -1;
                for(int i = 0 ; i < 26 ; i++)
                        next[i] = NULL;
                pre = p;
                fail = pre;
        };
};


bool yes[1024];
Trie* root;
int n;
char str[1000010];


//convert
int cv(int a)
{
        return a-'a';
}

void Insert(char word[], int num)
{
        Trie* p = root;
        for(int i = 0 ; word[i] ; i++)
        {
                Trie *& nxt = p->next[cv(word[i])];
                
                if(nxt == NULL)                // !!!
                {
                        nxt = new Trie(cv(word[i]), p);
                }
                p = nxt;
        }
        p->contain = num;
        
}

inline void Build_Fail()
{
        queue<Trie*> que;
        Trie* p = root;
        for(int i = 0 ; i < 26 ; i++)
                if(p->next[i] != NULL)
                        for(int j = 0 ; j < 26 ; j++)
                                if(p->next[i]->next[j] != NULL)
                                        que.push(p->next[i]->next[j]);        
        while(que.size())
        {
                p = que.front();        que.pop();
                while(p->fail != root)
                {
                        p->fail = p->fail->fail;
                        if(p->fail->next[p->number] != NULL)
                                break;
                }
                
                for(int i = 0 ; i < 26 ; i++)
                        if(p->next[i] != 0)
                                que.push(p->next[i]);
        }
}

inline void AC()
{
}

int main()
{
        int t;
        char word[64];
        
        scanf("%d", &t);
        while(t--)
        {
                scanf("%s", str);
                scanf("%d", &n);
                for(int i = 0 ; i < n ; i++)
                {
                        scanf("%s", word);
                        for(int j = 0 ; word[j] ; j++)
                                if('A' <= word[j] && word[j] <= 'Z')
                                        word[j] = word[j] + 'a'-'A';
                        Insert(word, i);
                }
                
                Build_Fail();
                
                AC();
        }
}

jd3

啊啊我自己發現問題了