定义
//定义和初始化
struct bign
{
int d[1000];
int len;
bign() {
memset(d, 0, sizeof(d));
len = 0;
}
};
//字符串转成结构体
bign change(char str[]) {
bign a;
a.len = strlen(str);
for (int i = 0; i < a.len; i++) {
a.d[i] = str[a.len - i - 1] - '0';
}
return a;
}
加法
//大数加法
bign add(bign a, bign b) {
bign c;
int carry = 0;
for (int i = 0; i < a.len || b.len; i++) {
int temp = a.d[i] + b.d[i] + carry;
c.d[c.len++] = temp%10;
carry = temp/10;
}
if (carry != 0) {
c.d[c.len++] = carry;
}
return c;
}
减法
//大数减法
bign sub(bign a, bign b) {
bign c;
for (int i = 0; i < a.len || b.len; i++) {
if (a.d[i] < b.d[i]) {//如果不够减
a.d[i + 1]--;
a.d[i] += 10;
}
c.d[c.len++] = a.d[i] - b.d[i];
}
//去除高位的0
while (c.len - 1 >= 1 && c.d[c.len - 1] == 0) {
c.len--;
}
}
乘法
//乘法,高精度数a除以int型b
bign multi(bign a, int b) {
bign c;
int carry = 0;//进位
for (int i = 0; i < a.len; i++) {
int temp = a.d[i] * b + carry;
c.d[c.len++] = temp%10;
carry = temp / 10;
}
while (carry != 0) {
c.d[c.len++] = carry % 10;//乘法的进位可能不止一位
carry /= 10;
}
return c;
}
除法
//除法
//除数a,被除数b,余数r
bign divide(bign a, int b, int& r) {
bign c;
c.len = a.len;//被除数的每一位和商的每一位是对应的,因此先令长度相等
for (int i = a.len - 1; i >= 0; i--) {
r = r*10 + a.d[i];
if (r < b) c.d[i] = 0;//不够除,该位为0
else {
c.d[i] = r/b;//商
r = r%b;//获得新的余数
}
}
while (c.len - 1 >= 1 && c.d[len - 1] == 0) {
c.len--;//去掉先导零
}
return c;
}
逆向输出
//逆向输出,因为是逆向存储的
void print(bign a) {
for (int i = a.len-1; i >= 0; i--) {
printf("%d", a.d[i]);
}
}