[luogu1627 CQOI2009] 中位数 (乱搞)

传送门

Solution

好水的题(ーー;)

Code

//By Menteur_Hxy
#include <map>
#include <queue>
#include <cmath>
#include <cstdio>
#include <vector>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#define Re register
#define Ms(a,b) memset(a,(b),sizeof(a))
#define Fo(i,a,b) for(Re int i=(a),_=(b);i<=_;i++)
#define Ro(i,a,b) for(Re int i=(b),_=(a);i>=_;i--)
using namespace std;
typedef long long LL;
typedef pair<int,int> PII;

inline LL read() {
	LL x=0,f=1;char c=getchar();
	while(!isdigit(c)) {if(c=='-')f=-f;c=getchar();}
	while(isdigit(c)) x=(x<<1)+(x<<3)+c-48,c=getchar();
	return x*f;
}

const int N=1e5+10;
int n,b,st,sum,ans;
int da[N],t1[N];
map <int,int> M;

int get(int x) {
	if(x>b) return 1;
	if(x==b) return 0;
	if(x<b) return -1;
}

int main() {
	n=read(),b=read();
	Fo(i,1,n) {da[i]=read();if(da[i]==b) st=i;}
	Ro(i,1,st) sum+=get(da[i]),M[sum]++;//,cout<<sum<<" ";cout<<endl;
	sum=0;
	Fo(i,st,n) sum+=get(da[i]),ans+=M[-sum];//,cout<<sum<<" ";cout<<endl;
	printf("%d",ans);
	return 0;
}