{"id":141,"date":"2010-03-06T12:29:00","date_gmt":"2010-03-06T04:29:00","guid":{"rendered":"http:\/\/localhost\/?p=141"},"modified":"2010-03-06T12:29:00","modified_gmt":"2010-03-06T04:29:00","slug":"vijos_1549_median","status":"publish","type":"post","link":"https:\/\/www.shuizilong.com\/wjmzbmr\/?p=141","title":{"rendered":"\u3010VIJOS 1549\u3011 \u4e2d\u4f4d\u6570"},"content":{"rendered":"

www.vijos.cn\/Problem_Show.asp<\/a>
\u4e5f\u662f[CQOI2009]\u4e2d\u4f4d\u6570\u56fe<\/a>
\u989d\u3002\u3002\u8bbeb\u6240\u5728\u4f4d\u7f6e\u4e3ax\uff0c
\u8bbe\u4e00\u4e2a\u6570\u5217S\u4e2d\u5927\u4e8eb\u7684\u6570\u7684\u6570\u91cf-\u5c0f\u4e8eb\u7684\u6570\u7684\u6570\u91cfF(S)
\u90a3\u4e48\u8fd9\u4e2a\u5e8f\u5217\u7531x\u5de6\u8fb9\u7684\u4e00\u4e9b\u548c\u53f3\u8fb9\u7684\u4e00\u4e9b\u6784\u6210\uff0c\u4e14F(Left)+F(Right)=0\u3002\u3002
\u90a3\u4e48\u5c31\u5f88\u7b80\u5355\u4e86\u3002\u3002\u4ecex\u5f80\u53f3\u626b\u63cf\u4e00\u904d\uff0c\u8bb0\u5f55\u6bcf\u4e2aF(S)\u51fa\u73b0\u4e86\u51e0\u6b21\uff0c\u653e\u5728Count\u6570\u7ec4\u91cc
\u518d\u5f80\u5de6\u626b\u63cf\u4e00\u904d\uff0c\u82e5\u5f53\u524dF\u503c\u4e3anow,\u53ea\u8981\u628a\u7b54\u6848+\u4e0aCount[-now]\u5c31\u53ef\u4ee5\u4e86
0ms1A\u3002\u3002\u771f\u662f\u723d\u554a\u3002\u3002
Code\uff1a
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<cstring>
#define rep(i,n) for(int i=0;i<n;i++)
#define pb push_back
using namespace std;
const int inf=~0U>>1;
const int maxn=1e5+10;
int main()
{
\/\/freopen("in","r",stdin);
int n,b;int A[maxn];
int C[maxn*2]={0};
cin>>n>>b;int x;
rep(i,n) scanf("%d",A+i),x=(A[i]==b?i:x);
int now=0;
C[now+maxn]++;
for(int i=x+1;i<n;i++)
{
if(A[i]>b) now++;
else now–;
C[now+maxn]++;
}
long long ans=0;
now=0;ans+=C[now+maxn];
for(int i=x-1;i>=0;–i)
{
if(A[i]>b) now++;
else now–;
ans+=C[maxn-now];
}
cout<<ans<<endl;
}
P.S\u6700\u8fd1\u5728\u505a\u4ee5\u524d\u6d59\u6c5f\u7701\u6570\u5b66\u7ade\u8d5b\u7684\u5377\u5b50\uff0c\u7a81\u7136\u7075\u673a\u4e00\u52a8\u60f3\u51fa\u4e86\u4e00\u9053\u7f16\u7a0b\u9898\uff0c\u5c31\u4ea4\u5230Vijos\u4e0a\u9762\u53bb\u4e86\u3002\u3002\u4e0d\u77e5\u9053\u80fd\u4e0d\u80fd\u901a\u8fc7\u56e7\u3002\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

www.vijos.cn\/Problem_Show.asp\u4e5f\u662f[CQOI2009]\u4e2d\u4f4d\u6570\u56fe\u989d\u3002\u3002\u8bbeb\u6240\u5728\u4f4d\u7f6e\u4e3ax\uff0c\u8bbe\u4e00\u4e2a\u6570\u5217S\u4e2d\u5927\u4e8eb\u7684\u6570\u7684\u6570\u91cf-\u5c0f\u4e8eb\u7684\u6570\u7684\u6570\u91cfF(S)\u90a3\u4e48\u8fd9\u4e2a\u5e8f\u5217\u7531x\u5de6\u8fb9\u7684\u4e00\u4e9b\u548c\u53f3\u8fb9\u7684\u4e00\u4e9b\u6784\u6210\uff0c\u4e14F(Left)+F(Right)=0\u3002\u3002\u90a3\u4e48\u5c31\u5f88\u7b80\u5355\u4e86\u3002\u3002\u4ecex\u5f80\u53f3\u626b\u63cf\u4e00\u904d\uff0c\u8bb0\u5f55\u6bcf\u4e2aF(S)\u51fa\u73b0\u4e86\u51e0\u6b21\uff0c\u653e\u5728Count\u6570\u7ec4\u91cc\u518d\u5f80\u5de6\u626b\u63cf\u4e00\u904d\uff0c\u82e5\u5f53\u524dF\u503c\u4e3anow,\u53ea\u8981\u628a\u7b54\u6848+\u4e0aCount[-now]\u5c31\u53ef\u4ee5\u4e860ms1A\u3002\u3002\u771f\u662f\u723d\u554a\u3002\u3002Code\uff1a#include<cstdio>#include<iostream>#include<algorithm>#include<string>#include<vector>#include<cstring>#define rep(i,n) for(int i=0;i<n;i++)#define pb push_backusing namespace std;const int inf=~0U>>1;const int maxn=1e5+10;int main(){ \/\/freopen("in","r",stdin); int n,b;int A[maxn]; int C[maxn*2]={0}; cin>>n>>b;int x; rep(i,n) scanf("%d",A+i),x=(A[i]==b?i:x); int now=0; C[now+maxn]++; for(int i=x+1;i<n;i++) { if(A[i]>b) now++; else now–; C[now+maxn]++; } long long ans=0; now=0;ans+=C[now+maxn]; for(int i=x-1;i>=0;–i) { if(A[i]>b) now++; else now–; ans+=C[maxn-now]; } cout<<ans<<endl;}P.S\u6700\u8fd1\u5728\u505a\u4ee5\u524d\u6d59\u6c5f\u7701\u6570\u5b66\u7ade\u8d5b\u7684\u5377\u5b50\uff0c\u7a81\u7136\u7075\u673a\u4e00\u52a8\u60f3\u51fa\u4e86\u4e00\u9053\u7f16\u7a0b\u9898\uff0c\u5c31\u4ea4\u5230Vijos\u4e0a\u9762\u53bb\u4e86\u3002\u3002\u4e0d\u77e5\u9053\u80fd\u4e0d\u80fd\u901a\u8fc7\u56e7\u3002\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[10],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/141"}],"collection":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=141"}],"version-history":[{"count":0,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/141\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=141"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=141"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=141"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}