POJ 3368

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn = 100000 + 131;
int Pos[maxn];
int Num[maxn];
int d[maxn][30];
int Fun[maxn];
int n, m;

void RMQ_init()
{
    for(int i = 0; i < n; ++i) d[i][0] = Fun[i];
    for(int j = 1; (1<<j) <= n; ++j)
        for(int i = 0; i + (1<<j) - 1 < n; ++i)
        d[i][j] = max(d[i][j-1], d[i+(1<<(j-1))][j-1]);
}

int RMQ(int L, int R)
{
    int k = 0;
    while((1<<(k+1)) <= R-L+1) k++;
    return max(d[L][k], d[R-(1<<k)+1][k]);
}

int main()
{
    while(scanf("%d",&n) != EOF)
    {
        if(n == 0) break;
        scanf("%d",&m);
        for(int i = 0; i < n; ++i) scanf("%d",&Num[i]);
        for(int i = 0; i < n; ++i)
        {
            if(i == 0) Fun[i] = 1;
            else
            {
                if(Num[i] == Num[i-1]) Fun[i] = Fun[i-1] + 1;
                else Fun[i] = 1;
            }
        }
        //for(int i = 0; i < n; ++i) cout << Fun[i];
        //cout <<endl;

        ////////////////////////
        int Now = Num[n-1], pos = n-1;
        for(int i = n-1; i >= 0; --i)
        {
            if(Num[i] == Now)
                Pos[i] = pos;
            else
            {
                Now = Num[i];
                Pos[i] = i;
                pos = i;
            }
        }
        /*for(int i = 0; i < n; ++i) cout << Pos[i];
        cout <<endl;*/
        //////////////////////////
        RMQ_init();
        //cout << RMQ(2,5) <<endl;
        int l, r;
        for(int i = 0; i < m; ++i)
        {
            scanf("%d%d",&l,&r);
            l--, r--;
            int t = Pos[l];
            //cout << t << endl;
            if(t >= r)
            {
                printf("%d\n",r-l+1);
                continue;
            }
            else
                printf("%d\n", max(t-l+1,RMQ(t+1,r)));
        }
    }
}