some programs!

cs101/dh_20260909_05_sum_fractions.cpp

@@ -0,0 +1,76 @@
+#include <iostream>
+#include <sstream>
+
+using namespace std;
+
+long long gcd(long long x, long long y) {
+    if (x < y) swap(x, y);
+    if (x % y == 0) { return y; }
+    return gcd(y, x % y);
+}
+
+class Fraction {
+public:
+    long long numerator = 0, denominator = 1;
+
+    void simplify() {
+        if (numerator == 0) { denominator = 1; }
+        long long g = gcd(numerator, denominator);
+        numerator /= g, denominator /= g;
+    }
+
+    Fraction operator+(const Fraction& other) const {
+        Fraction result{
+            numerator * other.denominator + denominator * other.numerator,
+            denominator * other.denominator
+        };
+        result.simplify();
+        return result;
+    }
+
+    Fraction operator+=(const Fraction& other) {
+        return *this = *this + other;
+    }
+
+    Fraction() = default;
+    Fraction(const long long n, const long long d) : numerator(n), denominator(d) { simplify(); }
+
+    Fraction(const string& s) {
+        stringstream ss(s);
+        long long n, d;
+        char slash;
+        if (ss >> n >> slash >> d && slash == '/') {
+            numerator = n, denominator = d;
+            simplify();
+        } else {
+            throw invalid_argument("String is not a fraction");
+        }
+    }
+
+    [[nodiscard]] string to_string() const {
+        if (denominator == 1) {
+            return std::to_string(numerator);
+        }
+        return std::to_string(numerator) + '/' + std::to_string(denominator);
+    }
+};
+
+int n;
+string s;
+Fraction ans;
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+    for (int _ = 0; _ < n; _++) {
+        // clog << ans.numerator << '/' << ans.denominator << endl;
+        cin >> s;
+        ans += Fraction(s);
+    }
+
+    cout << ans.to_string() << endl;
+
+    return 0;
+}