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 = 4000 * 1000 + 10;
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 = 1;
        head[0] = tot[0] = next[0] = 0;
    }

    void insert(char *s)
    {
        int u = 0, v, n = strlen(s);
        tot[0]++;
        for (int i = 0; i <= n; i++)
        {
            bool found = false;
            for (v = head[u]; v != 0; v = next[v])
            {
                if (ch[v] == s[i])
                {
                    found = true;
                    break;
                }
            }
            if (!found)
            {
                v = sz++;
                tot[v] = 0;
                ch[v] = s[i];
                next[v] = head[u];
                head[u] = v;
                head[v] = 0;
            }
            u = v;
            tot[u]++;
        }
    }

    void dfs(int depth, int u)
    {
        if (head[u] == 0)
            ans += tot[u] * (tot[u] - 1)*depth;
        else
        {
            int sum = 0;
            for (int v = head[u]; v != 0; v = next[v])
                sum += tot[v] * (tot[u] - tot[v]);
            ans += sum / 2 * (2 * depth + 1);
            for (int v = head[u]; v != 0; v = next[v])
                dfs(depth + 1, v);
        }
    }
}t;

int main()
{
    //freopen("D:\\txt.txt", "r", stdin);
    char str[1005];
    int kase = 0;
    while (~scanf("%d", &n), n)
    {
        t.init();
        while (n--)
        {
            scanf("%s", str);
            t.insert(str);
        }
        ans = 0;
        t.dfs(0,0);
        printf("Case %d: %lld\n", ++kase, ans);
    }
    return 0;
}