POJ --2104

  1 #include<iostream>
  2 #include<cstdio>
  3 #include<algorithm>
  4 #define MAX 100005
  5 using namespace std;
  6 class TreeNode
  7 {
  8     public:
  9         int left;
 10         int right;
 11         int mid;
 12 };
 13 int ToLeft[30][MAX];
 14 int val[30][MAX];
 15 TreeNode node[3*MAX];
 16 int sorted[MAX];
 17 void BuildTree(int k, int d, int l, int r)
 18 {
 19     node[k].left = l;
 20     node[k].right = r;
 21     node[k].mid = (l + r) >> 1;
 22     int mid = (l + r) >> 1;
 23     if(l == r)
 24         return ;
 25     int lsame = mid - l + 1;
 26     for(int i = l;i <= r; i ++)
 27     {
 28         if(val[d][i] < sorted[mid])
 29             lsame --;
 30     }
 31     int lpos = l;
 32     int rpos = mid + 1;
 33     for(int i = l;i <= r;i ++)
 34     {
 35         if(i == l)
 36             ToLeft[d][i] == 0;
 37         else
 38             ToLeft[d][i] = ToLeft[d][i-1];
 39         if(val[d][i] < sorted[mid])
 40         {
 41             ToLeft[d][i] ++;
 42             val[d+1][lpos++] = val[d][i];
 43         }
 44         else if(val[d][i] > sorted[mid])
 45             val[d+1][rpos++] = val[d][i];
 46         else
 47         {
 48             if(lsame)
 49             {
 50                 ToLeft[d][i] ++;
 51                 val[d+1][lpos++] = val[d][i];
 52                 lsame --;
 53             }
 54             else
 55                 val[d+1][rpos++] = val[d][i];
 56         }
 57     }
 58     BuildTree(k << 1, d + 1, l, mid);
 59     BuildTree(k << 1|1, d+1, mid + 1, r);
 60 }
 61 
 62 int Query(int l, int r, int k, int d, int idx)
 63 {
 64     if(l == r)
 65         return val[d][l];
 66     int s;
 67     int ss;
 68     if(node[idx].left == l)
 69     {
 70         s = ToLeft[d][r];
 71         ss = 0;
 72     }
 73     else
 74     {
 75         s = ToLeft[d][r] - ToLeft[d][l-1];
 76         ss = ToLeft[d][l-1];
 77     }
 78     if(s >= k)
 79     {
 80         int newl = node[idx].left + ss;
 81         int newr = node[idx].left + ss + s - 1;
 82         return Query(newl, newr, k, d + 1, idx << 1);
 83     }
 84     else
 85     {
 86         int bb = l - node[idx].left - ss;
 87         int b = r- l - s + 1;
 88         int newl = node[idx].mid + bb + 1;
 89         int newr = node[idx].mid + bb + b;
 90         return Query(newl, newr, k - s, d + 1, idx << 1|1);
 91     }
 92 }
 93 
 94 int main(int argc, char const *argv[])
 95 {
 96     int n, m;
 97     int l, r, k;
 98     //freopen("in.c", "r", stdin);
 99     while(~scanf("%d%d", &n, &m))
100     {
101         for(int i = 1;i <= n;i ++)
102         {
103             scanf("%d", &val[0][i]);
104             sorted[i] = val[0][i];
105         }
106         sort(sorted+1, sorted+n+1);
107         BuildTree(1, 0, 1, n);
108         for(int i = 0;i < m;i ++)
109         {
110             scanf("%d%d%d", &l, &r, &k);
111             printf("%d\n", Query(l, r, k, 0, 1));
112         }
113     }
114     return 0;
115 }