UVa 11732 strcmp()函数（左孩子右兄弟表示法）

 #include<iostream>
 #include<algorithm>
 #include<string>
 #include<cstring>
 #include<vector>
 using namespace std;

 const int maxn =  *  + ;
 int n;
 long long ans;

 struct Trie
 {
     int head[maxn];     //head[i]为第i个结点的左儿子编号
     int next[maxn];     //next[i]为第i个结点的右兄弟编号
     char ch[maxn];      //第i个结点上的字符
     int tot[maxn];
     int sz;

     void init()
     {
         sz = ;
         head[] = tot[] = next[] = ;
     }

     void insert(char *s)
     {
         int u = , v, n = strlen(s);
         tot[]++;
         for (int i = ; i <= n; i++)
         {
             bool found = false;
             for (v = head[u]; v != ; v = next[v])
             {
                 if (ch[v] == s[i])
                 {
                     found = true;
                     break;
                 }
             }
             if (!found)
             {
                 v = sz++;
                 tot[v] = ;
                 ch[v] = s[i];
                 next[v] = head[u];
                 head[u] = v;
                 head[v] = ;
             }
             u = v;
             tot[u]++;
         }
     }

     void dfs(int depth, int u)
     {
         if (head[u] == )
             ans += tot[u] * (tot[u] - )*depth;
         else
         {
             int sum = ;
             for (int v = head[u]; v != ; v = next[v])
                 sum += tot[v] * (tot[u] - tot[v]);
             ans += sum /  * ( * depth + );
             for (int v = head[u]; v != ; v = next[v])
                 dfs(depth + , v);
         }
     }
 }t;

 int main()
 {
     //freopen("D:\\txt.txt", "r", stdin);
     char str[];
     int kase = ;
     while (~scanf("%d", &n), n)
     {
         t.init();
         while (n--)
         {
             scanf("%s", str);
             t.insert(str);
         }
         ans = ;
         t.dfs(,);
         printf("Case %d: %lld\n", ++kase, ans);
     }
     return ;
 }