刘汝佳蓝书上说这题字符集较大，所以我先是尝试用了指针写法，然而总是TLE。看了看题解数组写法能过，改用数组写法就AC了。为什么呢？
指针写法

#include <stdio.h>
#include <string.h>
typedef long long ll;

ll ans;

struct node{
    int end, cnt;
    node *son[63];
};
node *root;

int num(char ch) {
    if (ch >= 'a' && ch <= 'z') return ch - 'a';
    if (ch >= 'A' && ch <= 'Z') return 26 + ch - 'A';
    return 52 + ch - '0';
}

void insert(char *s) {
    int len = strlen(s);
    node *u = root;
    for (int i = 0; i < len; ++i) {
        int ch = num(s[i]);
        if (u->son[ch] == NULL) u->son[ch] = new node();
        ans += (u->cnt - u->son[ch]->cnt) * (2 * i + 1);
        u->cnt++;
        u = u->son[ch];
    }
    ans += (u->cnt - u->end) * (2 * len + 1);
    ans += u->end * 2 * (len + 1);
    u->cnt++;
    u->end++;
}

int main() {
    int n, T = 0;;
    char s[1010];
    while (~scanf("%d", &n) && n) {
        ans = 0;
        root = new node();
        while (n--) {
            scanf("%s", s);
            insert(s);
        }
        printf("Case %d: %lld\n", ++T, ans);
    }
    return 0;
}

数组写法

#include <stdio.h>
#include <string.h>
typedef long long ll;

const int MAXN = 4e6 + 10;
int tot = 1, trie[MAXN][63], cnt[MAXN], end[MAXN];
ll ans;

int num(char ch) {
    if (ch >= 'a' && ch <= 'z') return ch - 'a';
    if (ch >= 'A' && ch <= 'Z') return 26 + ch - 'A';
    return 52 + ch - '0';
}

void insert(char *s) {
    int u = 1, len=strlen(s);
    for (int i = 0; i < len; ++i) {
        int ch = num(s[i]);
        if (!trie[u][ch]) trie[u][ch] = ++tot;
        ans += (cnt[u] - cnt[trie[u][ch]]) * (2 * i + 1);
        cnt[u]++;
        u = trie[u][ch];
    }
    ans += (cnt[u] - end[u]) * (2 * len + 1);
    ans += end[u] * 2 * (len + 1);
    cnt[u]++;
    end[u]++;
}

int main() {
    int n, T = 0;
    char s[1010];
    while (~scanf("%d", &n) && n) {
        memset(trie, 0, sizeof(trie));
        memset(end, 0, sizeof(end));
        memset(cnt, 0, sizeof(cnt));
        ans = 0;
        tot = 1;
        while (n--) {
            scanf("%s", s);
            insert(s);
        }
        printf("Case %d: %lld\n", ++T, ans);
    }
    return 0;
}