23 lines
353 B
C++
23 lines
353 B
C++
#include <bits/stdc++.h>
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using namespace std;
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//用例：
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/*
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20
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输出：
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10946
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*/
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int f[3];
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int n;
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int solve() {
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f[0] = 1, f[1] = 2;
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for (int i = 2; i < n; i++)
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f[i % 3] = f[(i - 1) % 3] + f[(i - 2) % 3];
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return f[(n - 1) % 3];
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}
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int main() {
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scanf("%d", &n);
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printf("%d\n", solve());
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return 0;
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} |