25 lines
507 B
C++
25 lines
507 B
C++
#include<iostream>
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#include<vector>
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#include<algorithm>
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using namespace std;
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int main()
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{
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int temp;
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while(cin>>temp&&temp!=-1)
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{
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vector<int> v;
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v.push_back(temp);
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while(cin>>temp&&temp!=0)
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v.push_back(temp);
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int sum=0;
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for(int i=0;i!=v.size();++i)
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{
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auto b=find(v.cbegin(),v.cend(),2*v[i]);
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if(b!=v.cend())
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sum++;
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}
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cout<<sum<<endl;
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}
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return 0;
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}
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