悬关 WA 0pts求调

#include<bits/stdc++.h>
#define maxn 200005
#define int long long
using namespace std;
int n,m,size,tot,sum;	
int a[maxn],ans[maxn],cnt[maxn],cnt_bl[maxn];//cnt_bl每块cnt之和 
int bl[maxn],block[maxn],ls[maxn],rs[maxn];
struct query{
	int l,r,id,k;
}q[maxn];
struct disc{
	int id,num;
}d[maxn];//离散化 
int rk[maxn];
bool cmp(query x,query y)
{
	if(bl[x.l] == bl[y.l])
        return x.r < y.r;
    return x.l < y.l;
}
bool cmp2(disc x,disc y)
{
	return x.num < y.num;
}
void discre()
{
	sort(d + 1,d + n + 1,cmp2);
    for(int i = 1;i <= n;i++)
    {
    	if(d[i].num != d[i - 1].num)
    		++tot;
    	rk[d[i].id] = tot;
	}
}

void add(int x)
{
	cnt[rk[x]]++;
	cnt_bl[ bl[rk[x]] ] += cnt[rk[x]] == 1; 
}
void del(int x)
{
	cnt[rk[x]]--;
	cnt_bl[ bl[rk[x]] ] -= cnt[rk[x]] == 0; 
}
int get_ans(int x)
{
	int res = 0,i;
	for(i = 1;i <= tot / size + 1;i++)
	{
		if(res + cnt_bl[i] >= x)
			goto nxt;
		res += cnt_bl[i];
	}
	return -1;
	nxt:
	for(int j = ls[i];j <= rs[i];j++)
	{
		if(res + (bool)cnt[i] == x)
			return cnt[i];
		res += (bool)cnt[i];
	}
}
signed main()
{
	cin >> n >> m;
	size = max(1.0,pow(n,2.0/3.0));
	for(int i = 1;i <= n;i++)
	{
		scanf("%lld",&a[i]);
		d[i].num = a[i];d[i].id = i;
		bl[i] = (i - 1) / size + 1;
	}
	discre();
	
	for(int i = 1;i <= m;i++)
        scanf("%lld%lld%lld",&q[i].l,&q[i].r,&q[i].k),q[i].id = i;
    sort(q + 1,q + m + 1,cmp);
    
    size = sqrt(tot);
    for(int i = 1;i <= tot;i++)
    {
    	bl[i] = (i - 1) / size + 1;
    	ls[i] = (int)((i - 1) / size) * size + 1;
		rs[i] = (int)((i - 1) / size + 1) * size;
//		if(bl[i] != bl[i - 1])
//			cout << ls[i] << '/' <<rs[i]<<endl;
	}
    int l = 1,r = 0;
    for(int i = 1;i <= m;i++)
    {
        while(l > q[i].l)
            add(--l);
        while(r < q[i].r)
            add(++r);
        while(l < q[i].l)
            del(l++);
        while(r > q[i].r)
            del(r--);
		//cout << l << "->" <<r <<endl;
        //cout <<cnt[1] << "/" << cnt[2] <<endl;
        int k = q[i].k;
        ans[q[i].id] = get_ans(k);
    }
    for(int i = 1;i <= m;i++)
    {
    	printf("%lld\n",ans[i]);
	}
}