[PAT解题报告] Rational Arithmetic
和1081很像，多了一些运算， 仍然是直接做，通分，别忘记最大公约数。还有输出上注意负数要加括号。
代码：
#include <cstdio>
#include <cstring>
#include <string>
using namespace std;
char s[111];
long long gcd(long long x,long long y) {
return y?gcd(y, x % y):x;
}
void print(long long x,long long y) {
if (y < 0) {
x = -x;
y = -y;
}
long long g = gcd((x < 0)?(-x):x, y);
x /= g;
y /= g;
if (x == 0) {
putchar('0');
return;
}
bool sign = false;
if (x < 0) {
sign = true;
printf("(-");
x = -x;
}
bool have = false;
if (x / y) {
printf("%lld",x / y);
have = true;
}
if (x % y) {
if (have) {
putchar(' ');
}
printf("%lld/%lld",x % y, y);
}
if (sign) {
putchar(')');
}
}
int main() {
long long a , b, c, d;
scanf("%lld/%lld %lld/%lld",&a,&b,&c,&d);
// a / b + c / d
print(a, b);
printf(" + ");
print(c, d);
printf(" = ");
print(a * d + b * c, b * d);
puts("");
print(a, b);
printf(" - ");
print(c, d);
printf(" = ");
print(a * d - b * c, b * d);
puts("");
print(a, b);
printf(" * ");
print(c, d);
printf(" = ");
print(a * c, b * d);
puts("");
print(a, b);
printf(" / ");
print(c, d);
printf(" = ");
if (c) {
print(a * d, b * c);
}
else {
printf("Inf");
}
puts("");
return 0;
}
原题链接： http://www.patest.cn/contests/pat-a-practise/1088
