18 lines
421 B
C++
18 lines
421 B
C++
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#include <bits/stdc++.h>
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using namespace std;
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int main() {
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int n;
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cin >> n; // n!+(n-1)!+(n-2)!+...+1!
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int sum = 0; //结果，累加和
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for (int i = n; i >= 1; i--) { //枚举 n,n-1,n-2,....,1
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//计算n这个数字的阶乘
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int res = 1;
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for (int j = i; j >= 1; j--) res *= j;
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sum += res;
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}
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cout << sum << endl;
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return 0;
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}
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