UVA

input

n 2<=n<=4000

s1

s2

...

sn

1<=len(si)<=1000

output

输出用strcmp()两两比较si,sj(i!=j)要比较的次数，结果在long long范围内（相同字符比较两次，不相同字符比较一次，包括''）

做法：由于字符集太大，要用左兄弟右儿子的trie保存字符，不用每次都开ch[62]个孩子

#include <cstdio>
#include <queue>
#include <cstring>
#include <iostream>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <ctime>
#include <cmath>
#include <cctype>
#define MAX 100000
#define LL long long
#define mod 20071027
struct node
{
    int sz;
    char val;
    node*ch[2];            //ch[1]兄弟，ch[0]儿子
    node()
    {
        ch[0]=ch[1]=NULL;
        sz=0;
    }
};
char word[1010];
int n,cas=1;
long long sum;
long long insert(char*s,node*u)
{
    long long sum=0,lastsz=u->sz++;
    for(;*s||*(s-1);s++)
    {
        if(!u->ch[0])            //易错，要先把新建的结点连接到父结点才能往下走，否则新建之后父节点无法再读取到该结点
        {
            u->ch[0]=new node;
            u->ch[0]->val=*s;
        }    
        for(u=u->ch[0];u->val!=*s;u=u->ch[1])
        {
            if(!u->ch[1])
            {
                u->ch[1]=new node;
                u->ch[1]->val=*s;
            }
        }    
        sum+=lastsz+u->sz;
        lastsz=u->sz++;
    }
    return sum;
}
/*//这样可以将父节点的ch和新建的结点绑定起来，传过来的是&root
long long insert(char*s,node**u)
{
    long long sum=0,lastsz=(*u)->sz++;
    for(;*s||*(s-1);s++)
    {
        printf("%p
",u);
        for(u=&((*u)->ch[0]);(*u)&&(*u)->val!=*s;u=&((*u)->ch[1]));
        if(*u==NULL)
        {
            *u=new node;
            (*u)->ch[0]=(*u)->ch[1]=NULL;
            (*u)->val=*s;
        }
        sum+=lastsz+(*u)->sz;
        lastsz=(*u)->sz++;
    }
    return sum;
}*/
void freenode(node*u)
{
    if(u==NULL) return;
    freenode(u->ch[0]);
    freenode(u->ch[1]);
    delete u;
}
int main()
{
    //freopen("/home/user/桌面/in","r",stdin);
    while(scanf("%d",&n)==1&&n)
    {
        sum=0;
        node *root=new node;
        while(n--)
        {
            scanf("%s",word);
            sum+=insert(word,root);
        }
        printf("Case %d: %lld
",cas++,sum);
        freenode(root);
    }
    //printf("time=%.3lf",(double)clock()/CLOCKS_PER_SEC);
    return 0;
}

my Code

#include <cstdio>  
#include <cstring>  
#include <iostream>  
#include <algorithm>  
using namespace std;  
  
#define repf(i,a,b) for(int i=(a);i<=(b);i++)  
typedef long long ll;  
  
const int N = 0;  
const int MAXNODE = 4000010;  
  
int n, cas;  
ll ans;  
char str[4001];  
  
struct STrie {  
    int son[MAXNODE];  
    int bro[MAXNODE];  
    int val[MAXNODE];  
    char ch[MAXNODE];  
    int sz;  
  
    STrie() { sz = 1; ch[0] = val[0] = bro[0] = son[0] = 0; }  
    void init() { sz = 1; ch[0] = val[0] = bro[0] = son[0] = 0; }  
    // inline int idx(char c) { return c - 'a'; }  
      
    void insert(char *s) {  
        int len = strlen(s), u = 0, p;  
        repf (i, 0, len) {  
            // check the brother of u  
            for (p = son[u]; p; p = bro[p]) {  
                if (ch[p] == s[i])  
                    break;  
            }  
            // cannot find out than insert  
            if (!p) {  
                p = sz++;  
                ch[p] = s[i];  
                bro[p] = son[u];  
                son[p] = 0;  
                val[p] = 0;  
                son[u] = p;  
            }  
            ans += (val[u] - val[p]) * (2 * i + 1);  
            if (len == i) {  
                ans += val[p] * (2 * i + 2);  
                val[p]++;  
            }  
            val[u]++;  
            u = p;  
        }  
    }  
} trie;  
  
int main() {  
    // ios_base::sync_with_stdio(0);  
    while (~scanf("%d", &n) && n) {  
        trie.init();  
        ans = 0;  
        repf (i, 0, n - 1) {  
            scanf("%s", str);  
            trie.insert(str);  
        }  
        printf("Case %d: %lld
", ++cas, ans);  
    }  
    return 0;  
}