First Exercise

Informatik_I/Exercise_1/Task_3/README.md

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+# Task
+
+Write a program resistance.cpp that computes the equivalent resistance of the following wiring:
+
+![circuit](./resistance.png)
+
+We assume that $R_1$, $R_2$, $R_3$, and $R_4$ have an integer valued resistance. After input of the four values, the program should output the result arithmetically rounded to the nearest integer.
+
+**Remark:** In order to facilitate the task, you may want to:
+
+- Conceptually divide the task into sub tasks. For example, start with computation of serial resistors $R_{12}$ and $R_{34}$.
+- Solve the task first naively using default rounding and then think about how to accomplish arithmetic rounding. Recall that $\text{round}(x) = [x + 0.5] \text{ }\forall \text{ } x \in \mathbb{R}$, i.e., a real number can be rounded arithmetically by adding $0.5$ to it and then rounding down. For example, $\text{round}(8,6) = [8.6 + 0.5] = [9.1] = 9$.
+
+You can find formulas for computing the total resistance in this [Wikipedia article](https://en.wikipedia.org/wiki/Resistor#Series_and_parallel_resistors).
+
+**Important:** using anything other than int (e.g., floating point numbers, long, or double long) is forbidden.
+
+**Important:** using if-else and any other branches is forbidden.

Informatik_I/Exercise_1/Task_3/resistance.cpp

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+#include <iostream>
+
+int main() {
+  int r1;
+  int r2;
+  int r3;
+  int r4;
+  int res;
+
+  std::cin >> r1;
+  std::cin >> r2;
+  std::cin >> r3;
+  std::cin >> r4;
+
+  int r12 = r1 + r2;
+  int r34 = r3 + r4;
+
+  res = (r12 * r34 + ((r12 + r34) / 2)) /
+        (r12 + r34); // By adding the average of r12 and r34, the result is
+                     // increased enough to get the correct rounded number
+
+  std::cout << res;
+
+  return 0;
+}