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Codeforces Round 987 (Div. 2) — C. Penchick and BBQ Buns

AC代码

就是要再深想一步,其实也没有那么复杂
27’s situation → odd num ≥ 27

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ans[1]=1,ans[10]=1,ans[26]=1;
ans[27]=2,ans[23]=2;

就是这样构建27的情况

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#include <iostream>
#include <cstring>
#include <algorithm>
#include <deque>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <cmath>
#include <bitset>
#include <iterator>
#include <random>
#include <iomanip>

using namespace std;
typedef long long ll;
const ll N=static_cast<ll>(2e5)+10;
ll n,T,ans[N];
bool perf[N]; // is perfect square ?
vector<ll> P;

int main()
{
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
cin>>T;
for(int i=1;i<=N;++i) {
if(i*i>N)
break;
perf[i*i]=true;
P.push_back(i*i);
}
for(int i=0;i<P.size();++i) {

}
while (T--) {
cin>>n;
for(int i=1;i<=n;++i)
ans[i]=0;
if(n==3 || n==1) {
cout<<-1<<endl;
continue;
}
if(n%2==0) {
for(int i=1;i<=n/2;++i)
cout<<i<<" "<<i<<" ";
cout<<endl;
continue;
}else if(n<=25){
cout<<-1<<endl;
continue;
}
// 27's situation -> odd num >= 27
ans[1]=1,ans[10]=1,ans[26]=1;
ans[27]=2,ans[23]=2;
ll kind=3,cnt=0;
for(int i=1;i<=n;++i) {
if(ans[i])
continue;
if(cnt%2==0)
++kind;
ans[i]=kind;
++cnt;
}
for(int i=1;i<=n;++i)
cout<<ans[i]<<" ";
cout<<endl;
}
}
// AC https://codeforces.com/contest/2031/submission/291725770

心路历程(WA,TLE,MLE……)

赛时我在想我要找到全部的完全平方数相加等于另一个完全平方数的这种,但后来发现根本不需要

详见上面