「2017 山东一轮集训 Day4」基因

设置 \(\sqrt{n}\) 个关键点，维护出关键点到每个右端点之间的答案以及Pam的左指针，每次暴力向左插入元素即可，为了去重，还需要记录一下Pam上每个节点在每个关键点为左端点插入到时候到最左边出现位置，总复杂度 \(O(n\sqrt{n})\)。

/*program by mangoyang*/
#pragma GCC optimize("Ofast", "inline")
#include<bits/stdc++.h>
#define inf ((int)(1e9))
#define Max(a, b) ((a) > (b) ? (a) : (b))
#define Min(a, b) ((a) < (b) ? (a) : (b))
typedef long long ll;
using namespace std;
template <class T>
inline void read(T &x){
    int f = 0, ch = 0; x = 0;
    for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = 1;
    for(; isdigit(ch); ch = getchar()) x = x * 10 + ch - 48;
    if(f) x = -x;
}
const int N = 100005;
char s[N];
namespace PAM{
    int fa[N], ch[N][26], trans[N][26], len[N], size, tail, head;
    inline void init(){
        fa[0] = 1, len[1] = -1, tail = head = size = 1;
        for(int i = 0; i < 26; i++) trans[0][i] = 1;
    }
    inline int newnode(int x){ return len[++size] = x, size; }
    inline void pushback(int l, int r){
        int c = s[r] - 'a', p = tail;
        while(r - len[p] - 1 < l || s[r-len[p]-1] != s[r]) p = fa[p];
        if(!ch[p][c]){
            int np = newnode(len[p] + 2); fa[np] = ch[trans[p][c]][c];
            memcpy(trans[np], trans[fa[np]], sizeof(trans[np]));
            trans[np][s[r-len[fa[np]]]-'a'] = fa[np], ch[p][c] = np;
        }
        tail = ch[p][c];
        if(len[tail] == r - l + 1) head = tail;
    }
    inline void pushfront(int l, int r){
        int c = s[l] - 'a', p = head;
        while(l + len[p] + 1 > r || s[l+len[p]+1] != s[l]) p = fa[p];
        if(!ch[p][c]){
            int np = newnode(len[p] + 2); fa[np] = ch[trans[p][c]][c];
            memcpy(trans[np], trans[fa[np]], sizeof(trans[np]));
            trans[np][s[l+len[fa[np]]]-'a'] = fa[np], ch[p][c] = np;
        }
        head = ch[p][c];
        if(len[head] == r - l + 1) tail = head;
    }
}


int bel[N], pos[700][N], pre[700][N], ans[700][N], ti[N], n, type, Q, Ans, tim;

int main(){
    read(type), read(n), read(Q);
    scanf("%s", s + 1);
    int S = (int) min(n, 150), block = (n / S) + (n % S > 0);
    PAM::init();
    for(int i = 1; i <= n; i++) bel[i] = (i - 1) / S + 1;
    for(int i = 1; i <= block; i++){
        PAM::tail = PAM::head = 1, ++tim;
        for(int j = (i - 1) * S + 1; j <= n; j++){
            PAM::pushback((i - 1) * S + 1, j);
            if(ti[PAM::tail] != tim) {
                ti[PAM::tail] = tim, pos[i][PAM::tail] = j, ans[i][j]++;
            }
            ans[i][j] += ans[i][j-1], pre[i][j] = PAM::head;
        }   
    }
    while(Q--){
        int l, r; read(l), read(r); 
        l ^= Ans * type, r ^= Ans * type, ++tim;
        if(bel[l] == bel[r]){
            PAM::head = PAM::tail = 1, Ans = 0;
            for(int i = l; i <= r; i++){
                PAM::pushback(l, i);
                if(ti[PAM::tail] != tim) ti[PAM::tail] = tim, Ans++;
            }
            printf("%d\n", Ans); continue;
        }
        int c = bel[l] + 1;
        PAM::head = pre[c][r], Ans = ans[c][r]; 
        for(int i = (c - 1) * S; i >= l; i--){
            PAM::pushfront(i, r);
            if(ti[PAM::head] != tim){
                ti[PAM::head] = tim;
                if(!pos[c][PAM::head] || pos[c][PAM::head] > r) Ans++;
            }
        }
        printf("%d\n", Ans);
    }   
    return 0;
}