BZOJ2223 [Coci 2009]PATULJCI

求区间内个数大于rank的一个数

主席树求一下就好啦！

 /**************************************************************
     Problem: 2223
     User: rausen
     Language: C++
     Result: Accepted
     Time:704 ms
     Memory:54712 kb
 ****************************************************************/

 #include <cstdio>
 #include <algorithm>

 using namespace std;
 const int N = 3e5 + ;
 const int Cnt_chair = ;

 struct chair_node {
     chair_node *ls, *rs;
     int cnt;
 } *root[N], mempool[Cnt_chair], *cnt_chair = mempool, *null;

 int n, mx, ans;

 inline int read() {
     int x = ;
     char ch = getchar();
     while (ch < '' || '' < ch)
         ch = getchar();
     while ('' <= ch && ch <= '') {
         x = x *  + ch - '';
         ch = getchar();
     }
     return x;
 }

 #define mid (l + r >> 1)
 void chair_insert(chair_node *p, chair_node *&q, int l, int r, int x) {
     (q = ++cnt_chair) -> cnt = p -> cnt + ;
     if (l == r) return;
     if (x <= mid)
         q -> rs = p -> rs, chair_insert(p -> ls, q -> ls, l, mid, x);
     else
         q -> ls = p -> ls, chair_insert(p -> rs, q -> rs, mid + , r, x);
 }

 int chair_query(chair_node *p, chair_node *q, int l, int r, int rank) {
     if (l == r) return l;
     if (q -> ls -> cnt - p -> ls -> cnt > rank)
         return chair_query(p -> ls, q -> ls, l, mid, rank);
     if (q -> rs -> cnt - p -> rs -> cnt > rank)
         return chair_query(p -> rs, q -> rs, mid + , r, rank);
     return ;
 }
 #undef mid

 int main() {
     int Q, i, l, r;
     n = read(), mx = read();
     null = cnt_chair;
     null -> cnt = , null -> ls = null -> rs = null;
     root[] = null;
     for (i = ; i <= n; ++i)
         chair_insert(root[i - ], root[i], , mx, read());
     Q = read();
     while (Q--) {
         l = read(), r = read();
         if (l > r) swap(l, r);
         ans = chair_query(root[l - ], root[r], , mx, (r - l + ) >> );
         if (ans == ) printf("no\n");
         else printf("yes %d\n", ans);
     }
     return ;
 }

(p.s. 数组开小了连WA两发。。。555)