标签：树状数组   区间第k大   数据结构   

KPI

6
in 874
query
out
in 24622
in 12194
query

Case #1:
874
24622

主席树随便搞搞就行。听别人说说树状数组也能搞，于是学习了下，果然神奇

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 1e4 + 10;
int c[maxn],tot;
void Modify(int x,int d)
{
	for(int i = x; i <= tot; i += i&-i) c[i] += d;
}
int findk(int k,int limt)
{
	int ans = 0,cnt = 0;
	for(int i = limt; i >= 0; i--) {
		ans += (1<<i);
		if(ans > tot || cnt + c[ans] >= k) ans -= (1<<i);
		else cnt += c[ans];
	}
	return ans + 1;
}
char Q[maxn];
int date[maxn],sorted[maxn];
int main(int argc, char const *argv[])
{
	int n;
	int cas = 1;
	while(scanf("%d",&n) == 1) {
		printf("Case #%d:\n",cas++);
		int cur = 1;
		for(int i = 1; i <= n; i++) {
			char cmd[10];
			scanf("%s",cmd);
			Q[i] = cmd[0];
			if(Q[i]=='i') {
				scanf("%d",date + cur);
				sorted[cur] = date[cur];
				++cur;
			}
		}
		tot = cur;
		memset(c,0,sizeof(c[0])*tot);
		sort(sorted+1,sorted+cur);
		int ql = 0,qr = 0;
		for(int i = 1; i <= n; i++) {
			if(Q[i]=='i') {
				++qr;
				int pos = lower_bound(sorted+1,sorted+cur,date[qr]) - sorted;
				Modify(pos,1);
			}else if(Q[i] == 'o') {
				++ql;
				int pos = lower_bound(sorted+1,sorted+cur,date[ql]) - sorted;
				Modify(pos,-1);
			}else {
				int k = (qr - ql + 2) >> 1;
				printf("%d\n",sorted[findk(k,18)]);
			}
		}
	}
	return 0;
}

hdu 5249区间第k大（学习了下树状数组的搞法）

标签：树状数组   区间第k大   数据结构   

原文地址：http://blog.csdn.net/acvcla/article/details/46279943