add c++ fraction class

Author: indy256

cpp/numbertheory/frac.cpp

@@ -0,0 +1,14 @@
+#include <bits/stdc++.h>
+#include "frac.h"
+
+using namespace std;
+using fracll = frac<long long>;
+
+// usage example
+int main() {
+    fracll x{1, 2};
+    fracll y{2, 3};
+    x -= y;
+    x = x.abs();
+    cout << x.a << "/" << x.b << endl;
+}

cpp/numbertheory/frac.h

@@ -0,0 +1,74 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+template<class T>
+struct frac {
+    T a, b;
+
+    frac(T a, T b = 1) : a{a}, b{b} {
+        normalize();
+    }
+
+    void normalize() {
+        if (b < 0) {
+            a = -a;
+            b = -b;
+        }
+        T g = gcd(::abs(a), b);
+        if (g != 0) {
+            a /= g;
+            b /= g;
+        }
+        this->a = a;
+        this->b = b;
+    }
+
+    bool operator<(frac lhs) const { return a * lhs.b < b * lhs.a; }
+
+    bool operator>(frac lhs) const { return a * lhs.b > b * lhs.a; }
+
+    frac operator-() const { return frac(-a, b); }
+
+    frac abs() const { return frac(::abs(a), b); }
+
+    frac &operator+=(frac rhs) {
+        a = a * rhs.b + b * rhs.a;
+        b *= rhs.b;
+        normalize();
+        return *this;
+    }
+
+    frac &operator-=(frac rhs) {
+        a = a * rhs.b - b * rhs.a;
+        b *= rhs.b;
+        normalize();
+        return *this;
+    }
+
+    frac &operator*=(frac rhs) {
+        a *= rhs.a;
+        b *= rhs.b;
+        normalize();
+        return *this;
+    }
+
+    frac &operator/=(frac rhs) {
+        a *= rhs.b;
+        b *= rhs.a;
+        normalize();
+        return *this;
+    }
+
+    friend frac operator+(frac lhs, frac rhs) { return lhs += rhs; }
+
+    friend frac operator-(frac lhs, frac rhs) { return lhs -= rhs; }
+
+    friend frac operator*(frac lhs, frac rhs) { return lhs *= rhs; }
+
+    friend frac operator/(frac lhs, frac rhs) { return lhs /= rhs; }
+
+    friend bool operator==(frac lhs, frac rhs) { return lhs.a == rhs.a && lhs.b == rhs.b; }
+
+    friend bool operator!=(frac lhs, frac rhs) { return !(lhs == rhs); }
+};