#define MAX_NUM 2000
//两个大数比较大小
int big(char s1[], char s2[])
{
int q = 0;
while (s1[q] == '0')
{
q++;
}
strcpy(s1, s1 + q);
if (strlen(s1) == 0)
{
s1[0] = '0';
s1[1] = 0;
}
q = 0;
while (s2[q] == '0')
{
q++;
}
strcpy(s2, s2+q);
if (strlen(s2) == 0)
{
s2[0] = '0';
s2[1] = 0;
}
int len1 = strlen(s1);
int len2 = strlen(s2);
if (len1 > len2)
{
return 1;
}
else if (len1 < len2)
{
return 0;
}
else
{
for (int i = 0; i < len1; i++)
{
if (s1[i] > s2[i])
{
return 1;
}
else if (s1[i] < s2[i])
{
return 0;
}
}
}
return 0;
}
//一个大数乘以t
void mul(char s[], int t, char re[])
{
int left = 0, len;
int k = 0;
int j = 0;
for (int i = strlen(s) - 1; i >= 0; i--)
{
k = t * (s[i] - '0') + left;
re[j++] = (k % 10) + '0';
left = k / 10;
}
while (left > 0)
{
re[j++] = (left % 10) + '0';
left /= 10;
}
re[j] = 0;
len = strlen(re);
char c;
for (int i = 0; i < len / 2; i++)
{
c = re[i];
re[i] = re[len - 1 - i];
re[len - 1 - i] = c;
}
}
//两个大数相减
void sub(char a[], char b[])
{
int left, len1, len2;
int temp;
len1 = strlen(a) - 1;
len2 = strlen(b) - 1;
left = 0;
while (len2 >= 0)
{
temp = a[len1] - b[len2] + left;
if (temp < 0)
{
temp += 10;
left = -1;
}
else
{
left = 0;
}
a[len1] = temp + '0';
len1--;
len2--;
}
while (len1 >= 0)
{
temp = a[len1] - '0' + left;
if (temp < 0)
{
temp += 10;
left = -1;
}
else
{
left = 0;
}
a[len1] = temp + '0';
len1--;
}
int j = 0;
while (a[j] == '0')
{
j++;
}
strcpy(a, a + j);
if (strlen(a) == 0)
{
a[0] = '0';
a[1] = 0;
}
}
//大数开方
void sqr(char s[], char re[])
{
char temp[MAX_NUM];
char left[MAX_NUM];
char p[MAX_NUM];
int i, j, len1, len2, q;
len1 = strlen(s);
if (len1 % 2 == 0)
{
left[0] = s[0];
left[1] = s[1];
left[2] = 0;
j = 2;
}
else
{
left[0] = s[0];
left[1] = 0;
j = 1;
}
re[0] = '0';
re[1] = 0;
q = 0;
while (j <= len1)
{
mul(re, 20, temp);
len2 = strlen(temp);
for (i = 9; i >= 0; i--)
{
temp[len2 - 1] = i + '0';
mul(temp, i, p);
if (! big(p, left))
{
break;
}
}
re[q++] = i + '0';
re[q] = 0;
sub(left, p);
len2 = strlen(left);
left[len2] = s[j];
left[len2 + 1] = s[j + 1];
left[len2 + 2] = 0;
j += 2;
}
}
//实例
int _tmain(int argc, _TCHAR* argv[])
{
char s[MAX_NUM];
//char s2[MAX_NUM];
char re[MAX_NUM];
int i;
while (scanf("%s", s) != EOF)
{
re[0] = 0;
sqr(s, re);
i = 0;
while (re[i] == '0')
{
i++;
}
strcpy(re, re+i);
printf("%s/n",re);
}
return 0;
}
More。。。
