HDU 3874 Necklace

莫队算法。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<algorithm>
using namespace std;

const int maxn = 50000 + 10;
int n, m;
int a[maxn],pos[maxn],cnt[1000000+10];
long long ans[200000+10], Ans;
int L, R;
struct X
{
    int l, r, id;
}s[200000+10];

bool cmp(const X&a, const X&b)
{
    if (pos[a.l] == pos[b.l]) return a.r < b.r;
    return a.l < b.l;
}

int main()
{
    int T; scanf("%d",&T);
    while (T--)
    {
        memset(cnt,0,sizeof cnt);
        scanf("%d", &n);
        int sz = sqrt(n);
        for (int i = 1; i <= n; i++)
        {
            pos[i] = i / sz;
            scanf("%d", &a[i]);
        }

        scanf("%d", &m);
        for (int i = 1; i <= m; i++) {
            scanf("%d%d", &s[i].l, &s[i].r);
            s[i].id = i;
        }
        sort(s + 1, s + 1 + m, cmp);
        Ans=0;
        for (int i = s[1].l; i <= s[1].r; i++)
        {
            cnt[a[i]]++;
            if(cnt[a[i]]==1) Ans=Ans+(long long)a[i];
        }
        ans[s[1].id] = Ans; L = s[1].l; R = s[1].r;

        for (int i = 2; i <= m; i++)
        {
            while (L < s[i].l)
            {
                cnt[a[L]]--;
                if(cnt[a[L]]==0) Ans=Ans-(long long)a[L];
                L++;
            }
            while (L > s[i].l)
            {
                L--;
                cnt[a[L]]++;
                if(cnt[a[L]]==1) Ans=Ans+(long long)a[L];
            }
            while (R < s[i].r)
            {
                R++;
                cnt[a[R]]++;
                if(cnt[a[R]]==1) Ans=Ans+(long long)a[R];
            }
            while (R > s[i].r)
            {
                cnt[a[R]]--;
                if(cnt[a[R]]==0) Ans=Ans-(long long)a[R];
                R--;
            }
            ans[s[i].id] = Ans;
        }

        for (int i = 1; i <= m; i++) printf("%lld
", ans[i]);
    }
    return 0;
}