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24 lines
633 B
24 lines
633 B
#include<cstdio>
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using namespace std;
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typedef long long LL;
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//帕斯卡公式求组合数，与埃筛、欧筛类似，是预处理中好多，再慢慢用
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const int N = 2010; //n的数值上限
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LL C[N][N]; //组合数数组
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void C3() {
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//预处理杨辉三角形
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for (int i = 0; i < N; i++) {
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//base case
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C[i][0] = C[i][i] = 1; //组合数C(n,0)=1 组合数C(n,n)=c(n,0)=1
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//递推生成其它组合数
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for (int j = 1; j < i; j++)
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C[i][j] = (C[i - 1][j] + C[i - 1][j - 1]);
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}
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}
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int main() {
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C3();
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printf("%lld\n", C[54][17]);
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return 0;
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} |