POJ 2104

#include<iostream>
#include<cstdio>
#include<algorithm>
#define MAX 100005
using namespace std;
class TreeNode
{
public:
int left;
int right;
int mid;
};
int ToLeft[30][MAX];
int val[30][MAX];
TreeNode node[3*MAX];
int sorted[MAX];
void BuildTree(int k, int d, int l, int r)
{
node[k].left = l;
node[k].right = r;
node[k].mid = (l + r) >> 1;
int mid = (l + r) >> 1;
if(l == r)
return ;
int lsame = mid - l + 1;
for(int i = l;i <= r; i ++)
{
if(val[d][i] < sorted[mid])
lsame --;
}
int lpos = l;
int rpos = mid + 1;
for(int i = l;i <= r;i ++)
{
if(i == l)
ToLeft[d][i] == 0;
else
ToLeft[d][i] = ToLeft[d][i-1];
if(val[d][i] < sorted[mid])
{
ToLeft[d][i] ++;
val[d+1][lpos++] = val[d][i];
}
else if(val[d][i] > sorted[mid])
val[d+1][rpos++] = val[d][i];
else
{
if(lsame)
{
ToLeft[d][i] ++;
val[d+1][lpos++] = val[d][i];
lsame --;
}
else
val[d+1][rpos++] = val[d][i];
}
}
BuildTree(k << 1, d + 1, l, mid);
BuildTree(k << 1|1, d+1, mid + 1, r);
}

int Query(int l, int r, int k, int d, int idx)
{
if(l == r)
return val[d][l];
int s;
int ss;
if(node[idx].left == l)
{
s = ToLeft[d][r];
ss = 0;
}
else
{
s = ToLeft[d][r] - ToLeft[d][l-1];
ss = ToLeft[d][l-1];
}
if(s >= k)
{
int newl = node[idx].left + ss;
int newr = node[idx].left + ss + s - 1;
return Query(newl, newr, k, d + 1, idx << 1);
}
else
{
int bb = l - node[idx].left - ss;
int b = r- l - s + 1;
int newl = node[idx].mid + bb + 1;
int newr = node[idx].mid + bb + b;
return Query(newl, newr, k - s, d + 1, idx << 1|1);
}
}

int main(int argc, char const *argv[])
{
int n, m;
int l, r, k;
//freopen("in.c", "r", stdin);
while(~scanf("%d%d", &n, &m))
{
for(int i = 1;i <= n;i ++)
{
scanf("%d", &val[0][i]);
sorted[i] = val[0][i];
}
sort(sorted+1, sorted+n+1);
BuildTree(1, 0, 1, n);
for(int i = 0;i < m;i ++)
{
scanf("%d%d%d", &l, &r, &k);
printf("%d\n", Query(l, r, k, 0, 1));
}
}
return 0;
}