ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#214007 | #2380. 中位数 | erican | 60 | 32ms | 5988kb | C++11 | 2.1kb | 2024-11-14 22:22:35 | 2024-11-14 23:10:32 |
answer
// Problem: A. 中位数
// Contest: undefined - NOIP2024训练赛 05
// URL: http://noi.ac/contest/1157/problem/2380
// Memory Limit: 1024 MB
// Time Limit: 1000 ms
// Challenger: Erica N
// ----
//
#include<bits/stdc++.h>
using namespace std;
#define rd read()
#define ull unsigned long long
#define int long long
#define pb push_back
#define itn int
#define ps second
#define pf first
#define rd read()
int read(){
int xx = 0, ff = 1;char ch = getchar();
while (ch < '0' || ch > '9'){
if (ch == '-')ff = -1;
ch = getchar();
}
while (ch >= '0' && ch <= '9')xx = xx * 10 + (ch - '0'), ch = getchar();
return xx * ff;
}
#define zerol = 1
#ifdef zerol
#define cdbg(x...) do { cerr << #x << " -> "; err(x); } while (0)
void err() {cerr << endl;}
template<template<typename...> class T, typename t, typename... A>
void err(T<t> a, A... x) {
for (auto v: a) cerr << v << ' ';err(x...);
}
template<typename T, typename... A>
void err(T a, A... x) {
cerr << a << ' ';err(x...);
}
#else
#define dbg(...)
#endif
const int N=6e5+5;
const int M=3e5;
const ull P=137;
const int INF=1e18+7;
/*
策略
*/
namespace BIT{
int c[N];
void change(int x,int v){
x+=M;
while(x<N){
c[x]+=v;
x+=x&-x;
}
}
int query(int x){
x+=M;
int res=0;
while(x){
res+=c[x];
x-=x&-x;
}
return res;
}
}using namespace BIT;
int pre[N];
int a[N],b[N];
int n;
int check(int x){
pre[0] = n + 1;
for(int i=1;i<=n;i++){
pre[i]=pre[i-1]+(a[i]>x ? -1 : 1);
}
memset(c,0,sizeof c);
int res=0;
change(pre[0],1);
for(int i=1;i<=n;i++){
res+=query(pre[i]);
// cdbg("UJD",i);
change(pre[i],1);
}
// cdbg(x,res);
return res;
}
signed main(){
n=rd;
for(int i=1;i<=n;i++){
b[i]=a[i]=rd;
}
int tot=(1+n)*n/2;
sort(b+1,b+n+1);
int len=unique(b+1,b+n+1)-b-1;
int l=1,r=len;
int res=0;
// cdbg(tot);
// cdbg("OK");
while(l<=r){
int mid=l+r>>1;
// cdbg(l,r);
if(check(b[mid])>=tot / 2)res=mid,r=mid-1;
else l=mid+1;
}
// cout << check(10) << '\n';
cout<<b[res]<<endl;
}
Details
小提示:点击横条可展开更详细的信息
Test #1:
score: 10
Accepted
time: 0ms
memory: 5876kb
input:
200 247837946 222748444 549404903 934970141 181690491 116150147 755881953 912914845 578004877 589768...
output:
411892743
result:
ok 1 number(s): "411892743"
Test #2:
score: 10
Accepted
time: 6ms
memory: 5880kb
input:
200 504553675 321343511 781936447 172776833 779139954 643752948 106 164 303976944 828799931 11502170...
output:
451369372
result:
ok 1 number(s): "451369372"
Test #3:
score: 10
Accepted
time: 0ms
memory: 5880kb
input:
200 738368650 91602659 340556191 835209882 409442204 656938221 258295858 90658347 126689369 56196859...
output:
420852999
result:
ok 1 number(s): "420852999"
Test #4:
score: 10
Accepted
time: 9ms
memory: 5984kb
input:
5000 300051244 685920750 122806687 315801142 33592358 339985437 262520930 380010194 687330910 550362...
output:
465193387
result:
ok 1 number(s): "465193387"
Test #5:
score: 10
Accepted
time: 11ms
memory: 5988kb
input:
5000 108135249 950186870 146626753 682580494 744412491 4159 995071655 157947560 668940645 878891308 ...
output:
466892796
result:
ok 1 number(s): "466892796"
Test #6:
score: 10
Accepted
time: 6ms
memory: 5984kb
input:
5000 246610103 780664789 678774940 716124165 518453378 300121008 135383319 939869983 430946660 13412...
output:
470507384
result:
ok 1 number(s): "470507384"
Test #7:
score: 0
Runtime Error
input:
300000 786856547 380253059 684225515 795392038 881780483 18437791 793783577 832330260 801624996 3466...
output:
result:
Test #8:
score: 0
Runtime Error
input:
300000 951000485 930070933 3566360 157114366 150196488 611226665 123590886 950624066 472150346 57976...
output:
result:
Test #9:
score: 0
Runtime Error
input:
300000 728509094 406128756 696166390 756254976 31403187 672131182 35544213 870708756 3659210 5227553...
output:
result:
Test #10:
score: 0
Runtime Error
input:
300000 804874490 52247250 546638789 400214210 383796618 47995083 814777769 507157584 466189162 28296...