84 lines
1.9 KiB
C++
84 lines
1.9 KiB
C++
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#include <bits/stdc++.h>
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using namespace std;
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#ifdef ONLINE_JUDGE
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#define dbg(...)
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#else
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#include "Assets/debug.h"
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#endif
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#define int long long
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#define ll long long
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#define endl '\n'
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#define all(x) x.begin(), x.end()
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#define sz(x) (int)(x).size()
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#define yes cout << "YES" << endl
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#define no cout << "NO" << endl
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#define rep(i,a,b) for(int i=a; i<b; ++i)
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#define rrep(i,a,b) for(int i=a; i>=b; --i)
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#define pb push_back
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#define ppb pop_back
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#define ins insert
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#define ff first
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#define ss second
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#define FAST (ios_base::sync_with_stdio(false), cin.tie(nullptr));
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ll pow(ll x,ll y,ll m=1e9+7){ll ans=1;x%=m;while(y){if(y&1)ans=(ans*x)%m;x=(x*x)%m;y>>=1;}return ans;}
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void solve()
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{
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int n,k;
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cin>>n>>k;
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map<int,vector<int>>m;
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rep(i,0,n)
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{
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int x;
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cin>>x;
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m[x%k].pb(x/k);
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}
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int odd=n&1, ans=0;
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for(auto it:m)
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{
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vector<int>&v=it.second;
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int len = sz(v);
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sort(all(v));
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if(len&1)
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{
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if(!odd)
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{
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cout<<-1<<endl;
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return;
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}
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odd--;
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if(len==1) continue;
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vector<int>pf(len,0),sf(len,0);
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pf[1]=v[1]-v[0];
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sf[len-2]=v[len-1]-v[len-2];
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for(int i=3; i<len; i+=2) pf[i]=pf[i-2]+v[i]-v[i-1];
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for(int i=len-4; i>=0; i-=2) sf[i]=sf[i+2]+v[i+1]-v[i];
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int mn=INT_MAX;
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for(int i=0; i<len; i+=2)
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{
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int sum=0;
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if(i>0) sum+=pf[i-1];
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if(i<len-1) sum+=sf[i+1];
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mn = min(mn,sum);
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}
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ans+=mn;
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}
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else
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{
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for(int i=1; i<len; i+=2) ans+=v[i]-v[i-1];
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}
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}
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cout<<ans<<endl;
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}
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signed main()
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{
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FAST;
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int TCS = 1;
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cin >> TCS;
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for (int TC = 1; TC <= TCS; ++TC)
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{
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// cout<<"Case "<<TC<<": ";
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solve();
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}
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}
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