题目链接：uva 11732 - strcmp() Anyone?

题目大意：给定n个串，然后两两之间比较，问说总共要比较多少次。

解题思路：字典树，建立出字典树，然后根据字典树的性质在节点记录有多少个字符串包含该节点。因为节点的个数比较多，所以用左孩子右兄弟的方法建立字典树。

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

using namespace std;
typedef long long ll;
const int maxn = 4000005;
const int maxl = 1005;

char type[maxn];
ll ans;
int sz, val[maxn];
int son[maxn], bro[maxn];

void init () {
    sz = 1;
    ans = 0;
    son[0] = bro[0] = val[0] = 0;
}

void insert (char* s) {
    int n = strlen(s);
    int u = 0;

    for (int i = 0; i <= n; i++) {
        int v = 0;
        for (int j = son[u]; j; j = bro[j]) {
            if (type[j] == s[i]) {
                v = j;
                ans += val[j] * 2;
            } else
                ans += val[j];
        }

        if (v == 0) {
            v = sz++;
            type[v] = s[i];
            val[v] = son[v] = 0;
            bro[v] = son[u];
            son[u] = v;
        }

        u = v;
        val[u]++;
    }
}

int main () {
    int cas = 1, n;
    char word[maxl];

    while (scanf("%d", &n) == 1 && n) {
        ans = 0;
        init();
        for (int i = 0; i < n; i++) {
            scanf("%s", word);
            insert(word);
        }

        printf("Case %d: %lld\n", cas++, ans);
    }
    return 0;
}

uva 11732 - strcmp() Anyone?(字典树)