HDU 1671 & POJ 3630 Phone List

题意

判断一组字符串中是否出现自己的前缀子串

思路

字典树

#include <stdio.h>
#include <string.h>
const int MAXN = 100010;
struct dicTree
{
    int next[10];
    bool isWord;
    void init(){
        memset(next,-1,sizeof(next));
        isWord = false;
    }
};
dicTree tree[MAXN];
int num;            
bool ok;

void insert(char *s){
    int index = 0 ,level = 1;
    while( *s ){
        int i = *s - '0';
        if( tree[index].next[i] == -1){
            tree[++num].init();        
            tree[index].next[i] = num;    
            index = num;                
        } else {        
              index = tree[index].next[i];
            if( tree[index].isWord == true ){ //判断长度小于等于当前插入单词的结尾
                ok = false;
                return;
            }
            
        }

        s++;
    }
    tree[index].isWord = true;
    for(int i = 0; i < 10; i++){    //判断单词长度大于当前插入单词的是否已经插入过
               if( tree[index].next[i] != -1 ){
            ok = false;
             break;
            }
    }
}
int main(){
    int t,n;
    char telNum[11];
    scanf("%d",&t);
    while( t-- ){
        scanf("%d",&n);
        ok = true;
        num = 0;
        tree[0].init();        
        while( n-- ){
            if( ok ){
                scanf("%s",telNum);
                insert(telNum);
            } else {//已经知道答案了 后面的数据可以忽略了
                scanf("%s",telNum);
            }
        }
        if( ok )
            printf("YES\n");
        else
            printf("NO\n");
    }
    return 0;
}