P3966 [TJOI2013]单词

Posted 2021-01-08 zgglj-com

题意：给n个单词，问每个单词在n个单词中出现了几次?  a 在 acdnsaana 中出现了4次。

ps：AC自动机的模板题，就注意一点：一定要从这棵树的底部向上遍历累加贡献。

const int N = 1000010;

struct node {
    int fail, Count;
    int vis[26];
    node() {
        mem(vis, 0);
        fail = Count = 0;
    }
};

struct AcToMation {
    node a[N];
    int tot, sum[N], id[300];

    stack<int> st;

    void Inite() {
        tot = 0;
        mem(sum, 0);
    }
    void Build(char *s, int t) {
        int n = strlen(s);
        int now = 0;
        rep(i, 0, n) {
            if (!a[now].vis[s[i] - ‘a‘]) a[now].vis[s[i] - ‘a‘] = ++tot;
            now = a[now].vis[s[i] - ‘a‘];
            sum[now]++;
        }
        a[now].Count++;
        id[t] = now;
    }
    void getFail() {
        queue<int> q;
        rep(i, 0, 26) if (a[0].vis[i]) {
            a[a[0].vis[i]].fail = 0;
            q.push(a[0].vis[i]);
        }
        while(!q.empty()) {
            int now = q.front();
            q.pop();
            st.push(now);
            rep(i, 0, 26) {
                if (a[now].vis[i]) {
                    a[a[now].vis[i]].fail = a[a[now].fail].vis[i];
                    q.push(a[now].vis[i]);
                }
                else {
                    a[now].vis[i] = a[a[now].fail].vis[i];
                }
            }
        }
    }
    void Compute(int n) {
        while(!st.empty()) {
            sum[a[st.top()].fail] += sum[st.top()];
            st.pop();
        }
        Rep(i, 1, n) pr(sum[id[i]]);
    }
};

AcToMation ac;


int main()
{
    ac.Inite();

    int n;
    char s[N];

    sc(n);
    Rep(i, 1, n) {
        scanf("%s", s);
        ac.Build(s, i);
    }
    ac.getFail();
    ac.Compute(n);
    return 0;
}