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  • UVa 10105 Polynomial Coefficients(排列组合)

    题意:

    x1n1x2n2...xknk的系数

    思路:

    排列组合知识。

    #include <cstdio>
    #include <cstdlib>
    #include <cstring>
    
    const int MAXN = 20;
    int c[MAXN][MAXN];
    
    void init()
    {
        for (int i = 0; i < MAXN; ++i)
            c[i][0] = c[i][i] = 1;
    
        for (int i = 2; i < MAXN; ++i)
            for (int j = 1; j < i; ++j)
                c[i][j] = c[i-1][j] + c[i-1][j-1];
    }
    
    int main()
    {
        int n, k;
        init();
        while (scanf("%d %d", &n, &k) != EOF)
        {
            int a[MAXN];
            for (int i = 0; i < k; ++i)
                scanf("%d", &a[i]);
    
            int ans = 1;
            for (int i = 0; i < k; ++i)
                ans *= c[n][a[i]], n -= a[i];
    
            printf("%d\n", ans);
        }
        return 0;
    }
    -------------------------------------------------------

    kedebug

    Department of Computer Science and Engineering,

    Shanghai Jiao Tong University

    E-mail: kedebug0@gmail.com

    GitHub: http://github.com/kedebug

    -------------------------------------------------------

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  • 原文地址:https://www.cnblogs.com/kedebug/p/2810457.html
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