这道题真的恶心，我花了一上午的时间才A。

对比了一下其他人的代码，我感觉自己的代码十分冗长。

分块肯定是要的，分块完以后处理一下块中各种花的前缀和，并对于同种花在同一个块内搞一个倍增，这样可以快速的找出同种花的个数。顺便记录每一个块开头到任意一个点的众数。

查询的时候只需要找左边不在整块内的花，然后用倍增和前缀和查找出所有同种类的花，然后比较最大值。

上面有很多细节已经省略，请看代码

#include <cstdio>
#include <cstring>
#include <iostream>
#include <cstdlib>
#include <algorithm>
#include <cmath>
using namespace std;
const int N = 4e4 + 10, M = 5e4 + 10, K = 210;
int n, m, q, a[N], b[N];
int get(int x) {
    int l = 1, r = m, mid, ans;
    while (l <= r) {
        mid = (l + r) >> 1;
        if (b[mid] <= x) ans = mid, l = mid + 1;
        else r = mid - 1;
    }
    return ans;
}

int cnt, L[K], R[K], p[N];
//s[K][N] 前缀和
//nxt[N][10] 倍增 
//head[K][N] 块中第一个 
//zs[K][N] 块头到某个点的众数，num[K][N]个数

int s[K][N], nxt[N][10], head[K][N], zs[K][N], num[K][N]; 

int last[N], sum[N];

bool vis[N]; int tp, sta[N];

int getl(int now) {
    int sum = 1;
    for (int j = 8; j >= 0; j--) 
        if (nxt[now][j]) now = nxt[now][j], sum += (1 << j);
    return sum;
}

int getr(int now, int y) {
    if (!now || now > y) return 0;
    int sum = 1, p = 1;
    while (p > 0) {
        if (!nxt[now][p - 1]) p--;
        else {
            if (nxt[now][p - 1] <= y) now = nxt[now][p - 1], sum += 1 << (p - 1), p++;
            else p--;
        }
    }
    return sum;
}

int main() {
    freopen("2.in", "r", stdin);
    cin >> n >> q;
    for (int i = 1; i <= n; i++) {
        scanf("%d", &a[i]);
        b[i] = a[i];
    }
    sort(b + 1, b + n + 1); m = 1;
    for (int i = 2; i <= n; i++)
        if (b[i] != b[i - 1]) b[++m] = b[i];
    for (int i = 1; i <= n; i++) a[i] = get(a[i]);
    int block = 3, cnt = (n - 1) / block + 1;
    for (int i = 1; i <= cnt; i++) {
        L[i] = R[i - 1] + 1;
        R[i] = R[i - 1] + block;
        if (i == cnt) R[i] = n;
        for (int j = L[i]; j <= R[i]; j++) p[j] = i;
    }
    for (int i = 1; i <= cnt; i++) {
        for (int j = 1; j <= m; j++) s[i][j] = s[i - 1][j], last[j] = sum[j] = 0;
        for (int j = L[i]; j <= R[i]; j++) {
            s[i][a[j]]++;
            if (head[i][a[j]] == 0) head[i][a[j]] = j;
            if (last[a[j]]) nxt[last[a[j]]][0] = j;
            last[a[j]] = j;
        }
        int maxx = 0;
        for (int j = L[i]; j <= n; j++) {
            sum[a[j]]++;
            if ((sum[a[j]] > sum[maxx]) || (sum[a[j]] == sum[maxx] && a[j] < maxx)) maxx = a[j];
            zs[i][j] = maxx; num[i][j] = sum[maxx];
        }
    }
    for (int j = 1; j <= 8; j++)
        for (int i = 1; i <= n; i++)
            nxt[i][j] = nxt[nxt[i][j - 1]][j - 1];
    int lastans = 0;
    for (int i = 1; i <= q; i++) {
        int x, y; scanf("%d%d", &x, &y);
        x = (x + lastans - 1) % n + 1;
        y = (y + lastans - 1) % n + 1;
        if (x > y) swap(x, y);
        int l = L[p[x]] == x ? p[x] : p[x] + 1;
        int r = R[p[y]] == y ? p[y] : p[y] - 1;
        if (l > r) {
            int maxx = 0, hh;
            if (p[x] == p[y]) {
                for (int i = x; i <= y; i++)
                    if (!vis[a[i]]) {
                        vis[a[i]] = 1; sta[++tp] = a[i];
                        int now = i, sum = getr(now, y);
                        if (sum > maxx || (sum == maxx && hh > a[i])) maxx = sum, hh = a[i];
                    }
            }
            else {
                for (int i = x; i <= y; i++) {
                    if (vis[a[i]]) continue;
                    vis[a[i]] = 1; sta[++tp] = a[i];
                    int sum = 0, now = i;
                    if (i <= R[p[x]]) sum += getl(now);
                    now = head[p[y]][a[i]];
                    sum += getr(now, y);
                    if (sum > maxx || (sum == maxx && hh > a[i])) maxx = sum, hh = a[i];
                }
            }
            printf("%d\n", lastans = b[hh]);
        }
        else {
            int p1 = zs[l][y], s1 = num[l][y];
            if (L[p[x]] == x) { printf("%d\n", lastans = b[p1]); continue;}
            int maxx = 0, hh;
            for (int i = x; i < L[l]; i++) {
                if (vis[a[i]]) continue;
                if (a[i] == p1) {s1++; continue;}
                vis[a[i]] = 1; sta[++tp] = a[i];
                int sum = s[r][a[i]] - s[l - 1][a[i]], now;
                now = i; sum += getl(now);
                if (y != R[p[y]]) now = head[p[y]][a[i]], sum += getr(now, y);
                if (sum > maxx || (sum == maxx && hh > a[i])) maxx = sum, hh = a[i];
            }
            if (s1 > maxx || (s1 == maxx && p1 < hh)) printf("%d\n", lastans = b[p1]);
            else printf("%d\n", lastans = b[hh]);
        }
        while (tp) vis[sta[tp--]] = 0;
    }
    return 0;
}