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44 lines
892 B
44 lines
892 B
#include <bits/stdc++.h>
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using namespace std;
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//功能：计算组合数公式
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typedef long long LL;
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const int N = 30;
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LL C[N][N];
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//组合数公式
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void getC() {
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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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//这个记忆的过程想一想杨辉三角就明白了,头顶+左上
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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 n, m;
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/**
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* 测试用例：
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* 4 2
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*
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* 答案：
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* 6
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*/
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int main() {
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cin >> n >> m;
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getC();
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/**
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* 输出杨辉三角
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*/
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for (int i = 0; i <= 20; i++) {
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for (int j = 0; j <= i; j++)
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cout << C[i][j] << ' ';
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cout << endl;
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}
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cout << C[n][m] << endl;
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return 0;
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} |