[bzoj2724]蒲公英

题目大意

经典分块

#include<cstdio>
#include<algorithm>
#include<cmath>
#define fo(i,a,b) for(i=a;i<=b;i++)
using namespace std;
typedef long long ll;
const int maxn=100000+10,maxc=300;
int ans[maxc][maxc],sum[maxn][maxc],cnt[maxn],a[maxn],b[maxn],belong[maxn];
int i,j,k,l,r,t,n,m,c,now;
int main(){
freopen("2724.in","r",stdin);freopen("2724.out","w",stdout);
scanf("%d%d",&n,&m);
c=floor(sqrt(n))+1;
fo(i,1,n) scanf("%d",&a[i]),belong[i]=(i-1)/c+1,b[i]=a[i];
sort(b+1,b+n+1);
l=unique(b+1,b+n+1)-b-1;
fo(i,1,n) a[i]=lower_bound(b+1,b+l+1,a[i])-b;
fo(i,1,belong
){
now=0;
fo(j,(i-1)*c+1,n){
cnt[a[j]]++;
if (!now||cnt[a[j]]>cnt[now]||cnt[a[j]]==cnt[now]&&a[j]<now) now=a[j];
ans[i][belong[j]]=now;
}
fo(j,(i-1)*c+1,n)
if (cnt[a[j]]) cnt[a[j]]=0;
}
fo(i,1,n) sum[a[i]][belong[i]]++;
fo(i,1,l)
fo(j,1,belong
)
sum[i][j]+=sum[i][j-1];
now=0;
while (m--){
scanf("%d%d",&j,&k);
j=(ll)(j+now-1)%n+1;k=(ll)(k+now-1)%n+1;
if (j>k) swap(j,k);
l=belong[j];r=belong[k];
if (r-l<=1){
now=0;
fo(i,j,k){
cnt[a[i]]++;
if (!now||cnt[a[i]]>cnt[now]||cnt[a[i]]==cnt[now]&&a[i]<now) now=a[i];
}
fo(i,j,k)
if (cnt[a[i]]) cnt[a[i]]=0;
now=b[now];
printf("%d\n",now);
continue;
}
now=ans[l+1][r-1];
fo(i,j,l*c){
cnt[a[i]]++;
if (!now||cnt[a[i]]+sum[a[i]][r-1]-sum[a[i]][l]>cnt[now]+sum[now][r-1]-sum[now][l]||cnt[a[i]]+sum[a[i]][r-1]-sum[a[i]][l]==cnt[now]+sum[now][r-1]-sum[now][l]&&a[i]<now) now=a[i];
}
fo(i,(r-1)*c+1,k){
cnt[a[i]]++;
if (!now||cnt[a[i]]+sum[a[i]][r-1]-sum[a[i]][l]>cnt[now]+sum[now][r-1]-sum[now][l]||cnt[a[i]]+sum[a[i]][r-1]-sum[a[i]][l]==cnt[now]+sum[now][r-1]-sum[now][l]&&a[i]<now) now=a[i];
}
fo(i,j,l*c)
if (cnt[a[i]]) cnt[a[i]]=0;
fo(i,(r-1)*c+1,k)
if (cnt[a[i]]) cnt[a[i]]=0;
now=b[now];
printf("%d\n",now);
}
}