bzoj 1005 HNOI2008 明明的烦恼

    这题做的我欲哭无泪啊……

    我已经没心情多说啥了……

    高精度T啊！我太弱啊！改了一天啊！还不如滚粗啊！

    想好式子在写啊！

    能用高精度乘单精度就不要用高精度乘高精度啊！

    能用高精度除单精度就不要用高精度除高精度啊！

    T成翔啊！

    简单的组合计数问题啊！

    题解在这里=_= : http://www.cnblogs.com/zhj5chengfeng/archive/2013/08/23/3278557.html

    上代码：

#include <cstdio>

#include <cstring>

#include <cstdlib>

#include <iostream>

#include <algorithm>

#include <cmath>

#define N 1100

using namespace std;

 

class bignum

{

    public:

        int l;

        int num[N*3];

        bignum(int nownum)

        {

            memset(num, 0, sizeof(num)); l = 0;

            if (nownum == 0) l = 1;

            else while (nownum)

            {

                num[++l] = nownum % 10;

                nownum /= 10;

            }

        }

        void jia(int y);

        void chu(int y);

        void cheng(int y);

        void print();

};

int n, d[N], sum = 0;

 

void bignum::jia (int y)

{

    num[1] += y; int d = num[1] / 10; int i = 1;

    while (d)

    {

        num[++i] = d;

        d = num[i] / 10;

        num[i] %= 10;

    }

    if (i > l) l = i;

}

 

void bignum::cheng (int y)

{

    for (int i = 1; i <= l; ++i)

        num[i] = num[i] * y;

    int d = 0;

    for (int i = 1; i <= l; ++i)

    {

        num[i] += d;

        d = num[i] / 10;

        num[i] %= 10;

    }

    while (d)

    {

        num[++l] = d;

        d = num[l] / 10;

        num[l] %= 10;

    }

    while (l > 1 && num[l] == 0) l--;

}

 

void bignum::chu (int y)

{

    int yu = 0;

    for (int i = l; i >= 1; --i)

    {

        yu = yu*10 + num[i];

        num[i] = yu / y;

        yu %= y;

    }

    while (l > 1 && num[l] == 0) l --;

}

 

void bignum::print()

{

    int d = 0;

    for (int i = 1; i <= l; ++i)

    {

        num[i] += d;

        d = num[i] / 10;

        num[i] %= 10;

    }

    while (d) { num[++l] += d; d = num[l] / 10; num[l] %= 10; }

    for (int i = l; i >= 1; --i) printf("%d", num[i]);

    printf("\n"); return;

}

 

int main()

{

    scanf("%d", &n); int fre = 0;

    for (int i = 1; i <= n; ++i)

    {

        scanf("%d", &d[i]);

        if (d[i] != -1) { fre++; sum += d[i]-1; }

    }

    if (sum > n-2)

    {

        printf("0\n");

        return 0;

    }

    bignum ans = 1;

    for (int i = n-1-sum; i <= n-2; ++i) ans.cheng(i);

    for (int i = 1; i <= n-sum-2; ++i) ans.cheng(n-fre);

    for (int i = 1; i <= n; ++i)

        if (d[i] > 2)

            for (int j = 2; j < d[i]; ++j) ans.chu(j);

    ans.print();

    return 0;

}