21 lines
428 B
C++
21 lines
428 B
C++
#include <bits/stdc++.h>
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using namespace std;
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typedef long long LL;
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//求组合数的优化后办法
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//优点：从1开始除和乘，可以防止过早溢出和除法除不尽
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LL C(int n, int m) {
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LL sum = 1;
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for (int i = 1; i <= m; i++)
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sum = sum * (n - m + i) / i;
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return sum;
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}
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int main() {
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int n = 10, m = 4;
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//组合公式法
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cout << C(n, m) << endl;
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return 0;
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} |