1 files changed, 147 insertions, 0 deletions
diff --git a/day13/part1.cpp b/day13/part1.cpp
new file mode 100644
index 0000000..b725edd
--- /dev/null
+++ b/day13/part1.cpp
@@ -0,0 +1,147 @@
+#include <iostream>
+#include <string>
+#include <vector>
+
+int consumeInt(std::string& s)
+{
+    int n = 0;
+    int i;
+
+    for (i = 0; s[i] >= '0' && s[i] <= '9'; ++i)
+        n = n * 10 + s[i] - '0';
+
+    s = s.substr(i);
+    return n;
+}
+
+// 5762 too high
+// 5659
+// 5632 too low
+
+int main()
+{
+    std::string left, right;
+    std::vector<int> correct;
+    int index = 1;
+
+    while (1) {
+        std::getline(std::cin, left);
+        if (std::cin.eof())
+            break;
+        std::getline(std::cin, right);
+        if (std::cin.eof())
+            break;
+
+        int lt = 0, rt = 0;
+
+        std::cout << left << std::endl;
+        std::cout << right << std::endl;
+
+        while (left.size() != 0 && right.size() != 0) {
+            if (left[0] == ']') {
+                if (right[0] != ']') {
+                    std::cout << "Left side ran out of items" << std::endl;
+                    correct.push_back(index);
+                    break;
+                }
+                if (rt) --rt;
+                else right = right.substr(1);
+                left = left.substr(1);
+            } else if (right[0] == ']') {
+                if (left[0] != ']') {
+                    std::cout << "Right side ran out of items" << std::endl;
+                    break; // incorrect
+                }
+                if (lt) --lt;
+                else left = left.substr(1);
+                right = right.substr(1);
+            } else if (left[0] == '[') {
+                std::cout << "Left side opens" << std::endl;
+                if (right[0] != '[')
+                    ++rt;
+                else
+                    right = right.substr(1);
+                left = left.substr(1);
+            } else if (right[0] == '[') {
+                std::cout << "Right side opens" << std::endl;
+                if (left[0] != '[')
+                    ++lt;
+                else
+                    left = left.substr(1);
+                right = right.substr(1);
+            } else {
+                int ln = consumeInt(left);
+                int rn = consumeInt(right);
+                std::cout << "Compare " << ln << " to " << rn << std::endl;
+
+                if (ln < rn) {
+                    correct.push_back(index);
+                    break;
+                } else if (ln > rn) {
+                    break;
+                }
+
+                int fail = 0;
+                while (rt) {
+                    if (left[0] != ']') {
+                        fail = 1;
+                        std::cout << "Right ends early" << std::endl;
+                        break;
+                    }
+
+                    left = left.substr(1);
+                    --rt;
+                }
+                while (lt) {
+                    if (right[0] != ']') {
+                        fail = 1;
+                        std::cout << "Left ends early" << std::endl;
+                        correct.push_back(index);
+                        break;
+                    }
+
+                    right = right.substr(1);
+                    --lt;
+                }
+                if (fail) break;
+            }
+
+            bool lcomma = left[0] == ',';
+            if (lcomma) {
+                left = left.substr(1);
+                if (right[0] != ',') {
+                    std::cout << "Right ends early" << std::endl;
+                    break;
+                }
+            }
+            if (right[0] == ',') {
+                right = right.substr(1);
+                if (!lcomma) {
+                    std::cout << "Left ends early" << std::endl;
+                    correct.push_back(index);
+                    break;
+                }
+            }
+        }
+
+        if (left.size() == 0 && right.size() == 0)
+            correct.push_back(index);
+
+        if (correct.size() > 0 && correct.back() == index)
+            std::cout << "  correct" << std::endl;
+        else
+            std::cout << std::endl;
+
+        index++;
+        std::getline(std::cin, left);
+        if (std::cin.eof())
+            break;
+    }
+
+    int sum = 0;
+    for (auto& w : correct)
+        sum += w;
+
+    std::cout << "Total corrects: " << sum << std::endl;
+}
+