Added older advents

advent_of_code_2019/day2/main1.cc

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+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+vector<int> read_input()
+{
+    vector<int> rval;
+    int buffer;
+    char comma;
+
+    while (cin)
+    {
+        cin >> buffer;
+        rval.push_back(buffer);
+        cin >> comma;
+    }
+
+    return rval;
+}
+
+int main(int argc, char *argv[])
+{
+    vector<int> program = read_input();
+    size_t instruction = 0;
+
+    // fix according to assignment
+    program[1] = 12;
+    program[2] = 2;
+
+    while(true)
+    {
+        switch(program[instruction++])
+        {
+            case 1:
+            {
+                size_t lhs = program[instruction++];
+                size_t rhs = program[instruction++];
+                size_t result = program[instruction++];
+                program[result] = program[lhs] + program[rhs];
+            }
+            break;
+
+            case 2:
+            {
+                size_t lhs = program[instruction++];
+                size_t rhs = program[instruction++];
+                size_t result = program[instruction++];
+                program[result] = program[lhs] * program[rhs];
+            }
+            break;
+
+            case 99:
+                cout << "Result: " << program[0] << "\n";
+                return 0;
+        }
+    }
+    
+}