aoc24: day02b not working

aoc.cpp

@@ -8,19 +8,21 @@
 
 #include "fmt/format.h"
 
-#include "aoc/24/01.hpp"
+using levels_t  = std::vector<std::int32_t>;
+using reports_t = std::vector<levels_t>;
 
 auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
-    constexpr auto filename = "./dat/24/re/01.txt";
-    std::ifstream strm{filename, std::ios::in};
+    // constexpr auto filename = "./dat/24/ex/02.txt";
+    constexpr auto filename = "./tmp.txt";
+    std::ifstream strm{filename, std::ios::in | std::ios::binary};
     if (!strm.is_open()) {
         fmt::print("Error opening file: {}\n", filename);
         return 1;
     }
 
-    std::vector<std::uint32_t> a{};
-    std::vector<std::uint32_t> b{};
+    reports_t reports{};
 
+    levels_t tmp{};
     std::string str{};
     while (strm) {
         auto const c = char(strm.peek());
@@ -28,45 +30,113 @@ auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
             str += char(strm.get());
             continue;
         }
-        if (c == ' ') {
-            if (!str.empty()) {
-                a.emplace_back(std::stoi(str));
-                str.clear();
-            }
+        if (c == ' ' && !str.empty()) {
+            tmp.emplace_back(std::stoi(str));
+            str.clear();
         }
-        if (c == '\n') {
-            if (!str.empty()) {
-                b.emplace_back(std::stoi(str));
-                str.clear();
-            }
+        if (c == '\n' && !str.empty()) {
+            tmp.emplace_back(std::stoi(str));
+            reports.emplace_back(std::move(tmp));
+            str.clear();
         }
-        [[discard]]strm.get();
+        strm.get();
     }
 
-    fmt::print("a: {}, b: {}\n", a.size(), b.size());
-
-    std::sort(std::begin(a), std::end(a));
-    std::sort(std::begin(b), std::end(b));
-
-    auto diff_view = std::views::zip(a, b) | std::views::transform([](auto const& p) {
-        auto const [x, y] = p;
-        return x > y ? x - y : y - x;
+    auto diff = reports | std::views::transform([](auto const& levels) {
+        return levels | std::views::adjacent_transform<2>([](auto const& a, auto const& b) {
+            return b - a;
+        });
     });
-    auto const sum = std::accumulate(std::begin(diff_view), std::end(diff_view), 0);
 
-    fmt::print("Part A: {}\n", std::abs(sum));
+    // condition: all increasing or all decreasing.
+    auto incdec = diff | std::views::filter([](auto const& levels) {
+        auto const n = std::ranges::all_of(levels, [](auto v) { return v < 0; });
+        auto const p = std::ranges::all_of(levels, [](auto v) { return v > 0; });
+        return n || p;
+    });
 
-    auto values = a | std::views::transform([&b](auto v) {
-        return std::pair{v, b | std::views::filter([v](auto c) {
-            return v == c; // Filter elements in `b` equal to `v`
-        }) | std::ranges::to<std::vector>()};
+    // condition: Any two adjacent levels differ by at least one and at most three.
+    auto adjdiff = incdec | std::views::filter([](auto const& levels){
+        return std::ranges::all_of(levels, [](auto v) {
+            return std::abs(v) <= 3;
+        });
+    });
+
+    auto const safe_reports = std::ranges::distance(adjdiff);
+
+    fmt::print("Part A: {}\n", safe_reports);
+
+    auto lefts = std::views::zip(diff, reports) | std::views::filter([](auto const& pair) {
+        auto const& [d, l] = pair;
+        auto const n = std::ranges::all_of(d, [](auto v) { return v < 0; });
+        auto const p = std::ranges::all_of(d, [](auto v) { return v > 0; });
+        return !(n || p);
+    }) | std::views::transform([](auto const& pair) {
+        auto const& [d, l] = pair;
+        return l;
+     });
+
+    auto masks = diff | std::views::filter([](auto const& vec) {
+        auto const n = std::ranges::all_of(vec, [](auto v) { return v < 0; });
+        auto const p = std::ranges::all_of(vec, [](auto v) { return v > 0; });
+        return !(n || p);
+    }) | std::views::transform([](auto const& vec) {
+        auto const p = std::count_if(std::begin(vec), std::end(vec), [](auto const& v) { return v >= 0; });
+        auto const n = std::count_if(std::begin(vec), std::end(vec), [](auto const& v) { return v < 0; });
+        auto mask = vec | std::views::transform([&](auto const& v) {
+                if (p > n) return v >= 0 ? 1 : 0;
+                else return v < 0 ? 1 : 0;
+            }) | std::ranges::to<std::vector>();
+        mask.push_back(1);
+        return mask;
+    });
+
+    auto const remain_reports = std::views::zip(masks, lefts)
+            | std::views::filter([](auto const& pair) {
+                auto const& [mask, level] = pair;
+                auto const n = std::count_if(std::begin(mask), std::end(mask), [](auto const& v) { return v == 0; });
+                return n == 1;
+            })
+            | std::views::transform([](auto const& pair){
+               auto const& [mask, level] = pair;
+
+               return std::views::zip(mask, level) | std::views::filter([](auto const& pair) {
+                    auto const& [m, v] = pair;
+                    return m == 1;
+               }) | std::views::transform([](auto const& pair) {
+                    auto const& [m, v] = pair;
+                    return v;
+               }) | std::ranges::to<std::vector>();
+            })
+            | std::ranges::to<std::vector>();
+
+    auto rem_diff = remain_reports | std::views::transform([](auto const& vec) {
+        return vec | std::views::adjacent_transform<2>([](auto const& a, auto const& b) { return b - a; });
+    });
+
+    auto safe_rems_vec = rem_diff | std::views::transform([](auto const& vec) {
+        return vec | std::views::filter([](auto const& a) {
+            return std::abs(a) <= 3;
+        }) | std::ranges::to<std::vector>();
     }) | std::ranges::to<std::vector>();
 
-    auto const meow = std::accumulate(std::begin(values), std::end(values), 0, [](auto const acc, auto const& pair) {
-        return acc + std::int32_t(pair.first * pair.second.size());
+    auto safe_rems = safe_rems_vec | std::views::filter([](auto const& vec) {
+        return vec.size() > 0;
+    }) | std::views::filter([](auto const& vec) {
+        auto const n = std::ranges::all_of(vec, [](auto v) { return v < 0; });
+        auto const p = std::ranges::all_of(vec, [](auto v) { return v > 0; });
+        return n || p;
     });
 
-    fmt::print("Part B: {}\n", meow);
+    auto const safe_reports_rem = std::ranges::distance(safe_rems);
+
+    // for (auto rep : safe_rems) {
+    //     for (auto v : rep) {
+    //         fmt::print("{} ", v);
+    //     }
+    //     fmt::print("\n");
+    // }
+    fmt::print("Part B: {}\n", safe_reports + safe_reports_rem);
 
     return 0;
 }

dat/24/ex/02.txt

@@ -0,0 +1,6 @@
+7 6 4 2 1
+1 2 7 8 9
+9 7 6 2 1
+1 3 2 4 5
+8 6 4 4 1
+1 3 6 7 9