POJ 1001 Exponentiation 高精浮点乘方

//POJ 1001 Exponentiation (百炼叫test)高精浮点乘方
//by 澄哥
#include <iostream>
#include <cstring>
#define MAX 200
using namespace std;

char* cut_zero(char *res)
{
    int headZero;
    int len = strlen(res);
    for (headZero = 0; headZero < len-1; headZero++)
        if (res[headZero]!='0')
            break;
    if(headZero)
        for (int i = 0; i <= len; i++)
            res[i] = res[i+headZero];
    return res;
}
char *big_mutiply(char a[], char b[])
{
    int la = strlen(a);
    int lb = strlen(b);
    int r[MAX] = {0};
    char* res = new char [MAX];
    int head = 0;
    for (int i = 0; i < la; i++)
        for (int j = 0; j < lb; j++)
            r[i+j] += (a[i]-'0')*(b[j]-'0');
    for (int i = la + lb - 2; i >= 0; i--)
    {
        if (i == 0)
        {
            head = r[0]/10;
            r[0] = r[0]%10;
        }
        else
        {
            r[i-1] += r[i]/10;
            r[i] = r[i]%10;
        }
    }
    if (head == 0)
    {
        for (int i = 0; i < la + lb -1; i++)
            res[i] = r[i]+'0';
        res[la + lb - 1] = '\0';
    }
    else
    {
        for (int i = la + lb - 2; i >= 0; i--)
            res[i+1] = r[i]+'0';
        res[0] = head + '0';
        res[la + lb] = '\0';
    }
    return cut_zero(res);
}
char *big_pow(char a[], int n)
{
    if (n == 0)
        return "1";
    if (n == 1)
            return cut_zero(a);
    if (n % 2 == 0)
        return big_mutiply(big_pow(a, n/2),big_pow(a, n/2));
    else
        return big_mutiply(big_pow(a, n/2),big_pow(a, n/2+1));
}
char* double_pow(char s[], int n)
{
    int dot = 0;
    char* s2 = new char[MAX];
    int len = strlen(s);
    for (int i = 0, j = 0; i <= len; i++)
    {
        if (s[i] == '.')
            dot = (len-i-1)*n;
        else
            s2[j++] = s[i];
    }
    strcpy(s2, big_pow(s2, n));
    if (dot == 0)    return s2;
    len = strlen(s2);
    if (len >= dot)
    {
        for (int i = len; i >= len - dot; i--)
            s2[i+1] = s2[i];
        s2[len-dot] = '.';
    }
    else
    {
        for (int i = len; i>= 0; i--)
            s2[i+dot-len+1] = s2[i];
        for (int i = 1; i <= dot - len; i++)
            s2[i] = '0';
        s2[0] = '.';
    }
    for (int i = strlen(s2)-1; i >= 0; i--)
    {
        if (s2[i] == '0')
        {
            s2[i] = '\0';                
        }
        else
        {
            if (s2[i] == '.')
                s2[i] = '\0';
            break;
        }
    }
    return s2;
}
int main()
{
    char s[10];
    int n;
    while(cin >> s >> n)
    {
        cout << double_pow(s, n) << endl;
    }
//    system("pause");
    return 0;
}