Day 2 challenges done

AdventOfCode2018/2ndDay/challenge2/main.cpp

@@ -0,0 +1,50 @@
+#include <string>
+#include <fstream>
+#include <iostream>
+#include <vector>
+
+std::string equalLetters(std::string fileName) {
+    std::fstream input(fileName);
+    std::string line;
+    std::string a;
+    std::string b;
+    std::string answer;
+    std::vector<std::string> lines;
+
+    while (!input.eof()) {
+        std::getline(input, line);
+        lines.push_back(line);
+    }
+
+    for (size_t i = 0; i < lines.size(); ++i) {
+        int count = 0;
+        a = lines[i];
+
+        for (size_t j = i + 1; j < lines.size(); ++j) {
+	    b = lines[j];
+	    count = 0;
+
+            for (size_t k = 0; k < a.size(); ++k) {
+                if (a[k] != b[k])
+		    ++count;
+		if (count > 1)
+		    break;
+	    }
+	    if (count == 1)
+	        break;
+        }
+        if (count == 1)
+	    break;
+    }
+
+    for (size_t i = 0; i < a.size(); ++i) {
+        if (a[i] == b[i])
+            answer += a[i];
+    }
+
+    return answer;
+}
+
+int main(int argc, char** argv) {
+    std::cout << "Found: " << equalLetters("input.txt") << std::endl;
+}