32 lines
425 B
C++
32 lines
425 B
C++
#include<cstdio>
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#include<vector>
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using namespace std;
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int answer(int n)
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{
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if(n<1) return 0;
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if(n==1) return 1;
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if(n==2) return 2;
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if(n==3) return 4;
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int a,b,c,d;
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a=1;
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b=2;
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c=4;
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d=0;
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for(int i=4;i<=n;i++)
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{
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d=a+b+c;
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a=b;
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b=c;
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c=d;
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}
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return d;
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}
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int main()
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{
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vector<int>ans;
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int x;
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while(scanf("%d",&x),x!=0) ans.push_back(answer(x));
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for(int i=0;i<ans.size();i++) printf("%d\n",ans[i]);
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return 0;
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}
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