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https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
21 lines
345 B
C++
21 lines
345 B
C++
#include<stdio.h>
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#include<iostream>
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#include<cstring>
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#include<cmath>
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using namespace std;
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typedef long long ll;
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int main()
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{
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ll a[51];
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a[1] = 3;
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a[2] = 6;
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a[3] = 6;
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for(int i=4;i<51;++i){
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a[i] = a[i-1] + 2*a[i-2];
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}
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int n;
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while(cin >> n && n){
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cout << a[n] << endl;
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}
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}
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