Codeforces 547E Mike and Friends 后缀数组

Mike and Friends

求出后缀数组， 对于每个询问二分出左右端点， 离线之后用树状数组求就好了。

或者不建st表， 用并查集求出左右端点， 这样空间和常数都更优。

#include<bits/stdc++.h>
#define LL long long
#define LD long double
#define ull unsigned long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ALL(x) (x).begin(), (x).end()
#define fio ios::sync_with_stdio(false); cin.tie(0);

using namespace std;

const int N = 5e5 + 7;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const double eps = 1e-8;
const double PI = acos(-1);

template<class T, class S> inline void add(T &a, S b) {a += b; if(a >= mod) a -= mod;}
template<class T, class S> inline void sub(T &a, S b) {a -= b; if(a < 0) a += mod;}
template<class T, class S> inline bool chkmax(T &a, S b) {return a < b ? a = b, true : false;}
template<class T, class S> inline bool chkmin(T &a, S b) {return a > b ? a = b, true : false;}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int r[N], sa[N], _t[N], _t2[N], c[N], rk[N], lcp[N], san;
int maxc = 'z' + 1;

void buildSa(int *r, int n, int m) {
    int i, j = 0, k = 0, *x = _t, *y = _t2;
    for(i = 0; i < m; i++) c[i] = 0;
    for(i = 0; i < n; i++) c[x[i] = r[i]]++;
    for(i = 1; i < m; i++) c[i] += c[i - 1];
    for(i = n - 1; i >= 0; i--) sa[--c[x[i]]] = i;
    for(int k = 1; k <= n; k <<= 1) {
        int p = 0;
        for(i = n - k; i < n; i++) y[p++] = i;
        for(i = 0; i < n; i++) if(sa[i] >= k) y[p++] = sa[i] - k;
        for(i = 0; i < m; i++) c[i] = 0;
        for(i = 0; i < n; i++) c[x[y[i]]]++;
        for(i = 1; i < m; i++) c[i] += c[i - 1];
        for(i = n - 1; i >= 0; i--) sa[--c[x[y[i]]]] = y[i];
        swap(x, y);
        p = 1; x[sa[0]] = 0;
        for(int i = 1; i < n; i++) {
            if(y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + k] == y[sa[i] + k])
                x[sa[i]] = p - 1;
            else x[sa[i]] = p++;
        }
        if(p >= n) break;
        m = p;
     }
     for(i = 1; i < n; i++) rk[sa[i]] = i;
     for(i = 0; i < n - 1; i++) {
        if(k) k--;
        j = sa[rk[i] - 1];
        while(r[i + k] == r[j + k]) k++;
        lcp[rk[i]] = k;
     }
}

struct Bit {
    int a[N];
    void modify(int x, int v) {
        for(int i = x; i < N; i += i & -i) {
            a[i] += v;
        }
    }
    int sum(int x) {
        int ans = 0;
        for(int i = x; i; i -= i & -i) {
            ans += a[i];
        }
        return ans;
    }
    int query(int L, int R) {
        if(L > R) return 0;
        return sum(R) - sum(L - 1);
    }
} bit;

int fa[N], dl[N], dr[N];

int getRoot(int x) {
    return fa[x] == x ? x : fa[x] = getRoot(fa[x]);
}

void Merge(int u, int v) {
    int x = getRoot(u);
    int y = getRoot(v);
    if(x == y) return;
    chkmin(dl[x], dl[y]);
    chkmax(dr[x], dr[y]);
    fa[y] = x;
}

struct Qus {
    int vl, vr, id;
};

int n, q, belong[N], len[N], sid[N];
int ans[N];
char s[N];
vector<Qus> Q[N];

int id[N], L[N], R[N], lcpId[N];

void printSuf(int x) {
    for(int i = sa[x]; i < san; i++) putchar((char)r[i]);
    for(int i = 0; i < (sa[x] + 5); i++) putchar(' ');
    printf("i: %3d  sa: %3d  lcp: %3d  belong: %3d
", x, sa[x], lcp[x], belong[sa[x]]);
}


int main() {
    scanf("%d%d", &n, &q);
    for(int i = 1; i <= n; i++) {
        if(i > 1) r[san++] = maxc++;
        scanf("%s", s);
        len[i] = strlen(s);
        sid[i] = san;
        for(int j = 0; s[j]; j++) {
            r[san] = s[j];
            belong[san++] = i;
        }
        id[i] = i;
    }
    r[san] = 0;
    buildSa(r, san + 1, maxc);

    for(int i = 1; i <= san; i++) {
        fa[i] = i;
        dl[i] = dr[i] = i;
        lcpId[i] = i;
    }

    sort(lcpId + 1, lcpId + san + 1, [&](int x, int y) {
        return lcp[x] > lcp[y];
    });

    sort(id + 1, id + 1 + n, [&](int x, int y) {
        return len[x] > len[y];
    });

    for(int i = 1, j = 1; i <= n; i++) {
        while(j <= san && lcp[lcpId[j]] >= len[id[i]]) {
            Merge(lcpId[j], lcpId[j] - 1);
            j++;
        }
        int Rt = getRoot(rk[sid[id[i]]]);
        L[id[i]] = dl[Rt];
        R[id[i]] = dr[Rt];
    }
//    puts("");
//    for(int i = 1; i <= san; i++) {
//        printSuf(i);
//    }
    for(int i = 1; i <= q; i++) {
        int l, r, k;
        scanf("%d%d%d", &l, &r, &k);
        Q[L[k] - 1].push_back(Qus{l, r, -i});
        Q[R[k]].push_back(Qus{l, r, i});
    }
    for(int i = 1; i <= san; i++) {
        if(belong[sa[i]]) {
            bit.modify(belong[sa[i]], 1);
        }
        for(auto &q : Q[i]) {
            if(q.id > 0) ans[q.id] += bit.query(q.vl, q.vr);
            else ans[-q.id] -= bit.query(q.vl, q.vr);
        }
    }
    for(int i = 1; i <= q; i++) {
        printf("%d
", ans[i]);
    }
    return 0;
}

/*
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