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33 lines
439 B
C++
33 lines
439 B
C++
#include<iostream>
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using namespace std;
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bool a[20010];
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int b[20010];
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int main()
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{
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int n, x, sum = 0;
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cin >> n;
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for(int i = 1; i <= n; i ++ )
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{
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cin >> x;
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a[x] = 1;
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}
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for(int i = 1; i <= 10000; i ++ )
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{
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if(a[i] == 1)
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{
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for(int j = i + 1; j <= 10000; j ++ )
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{
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if(a[j] == 1 && a[i + j] == 1)
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b[i + j] ++ ;
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}
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}
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}
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for(int i = 1; i <= 20010; i ++ )
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{
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if(b[i] >= 1)
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sum ++ ;
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}
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cout << sum;
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return 0;
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} |