ACM高精度加减乘除模板

【转】
#include <iostream>

#include <string>

using namespace std;

inline int compare(string str1, string str2)

{

if(str1.size() > str2.size()) //长度长的整数大于长度小的整数

return ;

else if(str1.size() < str2.size())

return -;

else

return str1.compare(str2); //若长度相等，从头到尾按位比较，compare函数：相等返回0，大于返回1，小于返回－1

}

//高精度加法

string ADD_INT(string str1, string str2)

{

string MINUS_INT(string str1, string str2);

int sign = ; //sign 为符号位

string str;

if(str1[] == '-') {

if(str2[] == '-') {

sign = -;

str = ADD_INT(str1.erase(, ), str2.erase(, ));

}else {

str = MINUS_INT(str2, str1.erase(, ));

}

}else {

if(str2[] == '-')

str = MINUS_INT(str1, str2.erase(, ));

else {

//把两个整数对齐，短整数前面加0补齐

string::size_type l1, l2;

int i;

l1 = str1.size(); l2 = str2.size();

if(l1 < l2) {

for(i = ; i <= l2 - l1; i++)

str1 = "" + str1;

}else {

for(i = ; i <= l1 - l2; i++)

str2 = "" + str2;

}

int int1 = , int2 = ; //int2 记录进位

for(i = str1.size() - ; i >= ; i--) {

int1 = (int(str1[i]) -  + int(str2[i]) -  + int2) % ; //48 为 '0' 的ASCII码

int2 = (int(str1[i]) -  + int(str2[i]) -  +int2) / ;

str = char(int1 + ) + str;

}

if(int2 != ) str = char(int2 + ) + str;

}

}

//运算后处理符号位

if((sign == -) && (str[] != ''))

str = "-" + str;

return str;

}

//高精度减法

string MINUS_INT(string str1, string str2)

{

string MULTIPLY_INT(string str1, string str2);

int sign = ; //sign 为符号位

string str;

if(str2[] == '-')

str = ADD_INT(str1, str2.erase(, ));

else {

int res = compare(str1, str2);

if(res == ) return "";

if(res < ) {

sign = -;

string temp = str1;

str1 = str2;

str2 = temp;

}

string::size_type tempint;

tempint = str1.size() - str2.size();

for(int i = str2.size() - ; i >= ; i--) {

if(str1[i + tempint] < str2[i]) {

str1[i + tempint - ] = char(int(str1[i + tempint - ]) - );

str = char(str1[i + tempint] - str2[i] + ) + str;

}

else

str = char(str1[i + tempint] - str2[i] + ) + str;

}

for(i = tempint - ; i >= ; i--)

str = str1[i] + str;

}

//去除结果中多余的前导0

str.erase(, str.find_first_not_of(''));

if(str.empty()) str = "";

if((sign == -) && (str[] != ''))

str = "-" + str;

return str;

}

//高精度乘法

string MULTIPLY_INT(string str1, string str2)

{

int sign = ; //sign 为符号位

string str;

if(str1[] == '-') {

sign *= -;

str1 = str1.erase(, );

}

if(str2[] == '-') {

sign *= -;

str2 = str2.erase(, );

}

int i, j;

string::size_type l1, l2;

l1 = str1.size(); l2 = str2.size();

for(i = l2 - ; i >= ; i --) { //实现手工乘法

string tempstr;

int int1 = , int2 = , int3 = int(str2[i]) - ;

if(int3 != ) {

for(j = ; j <= (int)(l2 -  - i); j++)

tempstr = "" + tempstr;

for(j = l1 - ; j >= ; j--) {

int1 = (int3 * (int(str1[j]) - ) + int2) % ;

int2 = (int3 * (int(str1[j]) - ) + int2) / ;

tempstr = char(int1 + ) + tempstr;

}

if(int2 != ) tempstr = char(int2 + ) + tempstr;

}

str = ADD_INT(str, tempstr);

}

//去除结果中的前导0

str.erase(, str.find_first_not_of(''));

if(str.empty()) str = "";

if((sign == -) && (str[] != ''))

str = "-" + str;

return str;

}

//高精度除法

string DIVIDE_INT(string str1, string str2, int flag)

{

//flag = 1时,返回商; flag = 0时,返回余数

string quotient, residue; //定义商和余数

int sign1 = , sign2 = ;

if(str2 == "") { //判断除数是否为0

quotient = "ERROR!";

residue = "ERROR!";

if(flag == ) return quotient;

else return residue;

}

if(str1 == "") { //判断被除数是否为0

quotient = "";

residue = "";

}

if(str1[] == '-') {

str1 = str1.erase(, );

sign1 *= -;

sign2 = -;

}

if(str2[] == '-') {

str2 = str2.erase(, );

sign1 *= -;

}

int res = compare(str1, str2);

if(res < ) {

quotient = "";

residue = str1;

}else if(res == ) {

quotient = "";

residue = "";

}else {

string::size_type l1, l2;

l1 = str1.size(); l2 = str2.size();

string tempstr;

tempstr.append(str1, , l2 - );

//模拟手工除法

for(int i = l2 - ; i < l1; i++) {

tempstr = tempstr + str1[i];

for(char ch = ''; ch >= ''; ch --) { //试商

string str;

str = str + ch;

if(compare(MULTIPLY_INT(str2, str), tempstr) <= ) {

quotient = quotient + ch;

tempstr = MINUS_INT(tempstr, MULTIPLY_INT(str2, str));

break;

}

}

}

residue = tempstr;

}

//去除结果中的前导0

quotient.erase(, quotient.find_first_not_of(''));

if(quotient.empty()) quotient = "";

if((sign1 == -) && (quotient[] != ''))

quotient = "-" + quotient;

if((sign2 == -) && (residue[] != ''))

residue = "-" + residue;

if(flag == ) return quotient;

else return residue;

}

//高精度除法,返回商

string DIV_INT(string str1, string str2)

{

return DIVIDE_INT(str1, str2, );

}

//高精度除法,返回余数

string MOD_INT(string str1, string str2)

{

return DIVIDE_INT(str1, str2, );

}

int main()

{

char ch;

string s1, s2, res;

while(cin >> ch) {

cin >> s1 >> s2;

switch(ch) {

case '+': res = ADD_INT(s1, s2); break; //高精度加法

case '-': res = MINUS_INT(s1, s2); break; //高精度减法

case '*': res = MULTIPLY_INT(s1, s2); break; //高精度乘法

case '/': res = DIV_INT(s1, s2); break; //高精度除法,返回商

case 'm': res = MOD_INT(s1, s2); break; //高精度除法,返回余数

default : break;

}

cout << res << endl;

}

return();

}