day 2

Makefile

@@ -17,8 +17,8 @@ ok-%: %_test.txt
 test-%: %_output.txt
 
 %_output.txt: %_test.txt
-	@test -f $@ || (echo $<:; cat $<)
-	@test -f $@ && (diff -u $@ $< && touch $@)
+	@test -f $@ || (echo $*:; cat $<)
+	@test -f $@ && (diff -u $@ $< && touch $@) || exit 0
 
-$(addsuffix _test.txt,$(progs)): %_test.txt: %
+$(addsuffix _test.txt,$(progs)): %_test.txt: % %_input.txt
 	./$< < $*_input.txt > $@

d02.cc

@@ -0,0 +1,48 @@
+#include <iostream>
+#include <vector>
+#include <array>
+
+using namespace std;
+
+vector<array<unsigned, 2>> parse()
+{
+    vector<array<unsigned, 2>> input;
+    string line;
+    while (getline(cin, line)) {
+        if (line.size() < 3 || line[1] != ' ') abort();
+        unsigned oppo = line[0] - 'A';
+        unsigned user = line[2] - 'X';
+        if (oppo >= 3 || user >= 3) abort();
+        input.push_back({oppo, user});
+    }
+    return input;
+}
+
+unsigned p1(vector<array<unsigned, 2>> &input)
+{
+    unsigned score = 0;
+    for (array<unsigned, 2> i : input) {
+        unsigned shape = i[1];
+        unsigned outcome = (i[1] - i[0] + 4) % 3;
+        score += shape + 1 + outcome * 3;
+    }
+    return score;
+}
+
+unsigned p2(vector<array<unsigned, 2>> &input)
+{
+    unsigned score = 0;
+    for (array<unsigned, 2> i : input) {
+        unsigned shape = (i[1] + i[0] + 2) % 3;
+        unsigned outcome = i[1];
+        score += shape + 1 + outcome * 3;
+    }
+    return score;
+}
+
+int main()
+{
+    auto input = parse();
+    cout << p1(input) << endl;
+    cout << p2(input) << endl;
+}

d02_output.txt

@@ -0,0 +1,2 @@
+13009
+10398