66 lines
963 B
C++
66 lines
963 B
C++
#include<bits/stdc++.h>
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using namespace std;
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using ll = long long;
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void solve()
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{
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int n;
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cin>>n;
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int ct1=0, ct2=0, ct3=0, ct4=0;
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for(int i=0; i<n; ++i)
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{
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int x;
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cin>>x;
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if(x==1)
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ct1++;
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else if(x==2)
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ct2++;
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else if(x==3)
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ct3++;
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else
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ct4++;
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}
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int taxi=ct4;
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if(ct2>1)
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{
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taxi=taxi+ct2/2;
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ct2=ct2%2;
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}
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while(ct3>0 && ct1>0)
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{
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taxi++;
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ct3--;
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ct1--;
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}
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if(ct3>0)
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taxi=taxi+ct3;
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if(ct1>0 && ct2>0)
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{
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taxi++;
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ct2--;
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ct1=ct1-2;
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}
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while(ct2>0)
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{
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taxi++;
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ct2--;
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}
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while(ct1>0)
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{
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taxi++;
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ct1=ct1-4;
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}
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cout<<taxi<<endl;
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}
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int main()
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{
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ios_base::sync_with_stdio(false);
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cin.tie(nullptr);
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int TC = 1;
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//cin >> TC;
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//cin.ignore();
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while (TC--) solve();
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} |