advent2024

commit f4934645b1133917a1f27ec042a2b338a0e19099
parent 2cd8129387019cd02e58cc2fb6c774b059f2588e
Author: bsandro <email@bsandro.tech>
Date:   Sun,  8 Dec 2024 19:53:30 +0200

Day 08 p2

Diffstat:
M
day08/main.cpp
 | 
61
++++++++++++++++++++++++++++++++++++++++++++-----------------
A
day08/test2.txt
 | 
10
++++++++++

2 files changed, 54 insertions(+), 17 deletions(-)
diff --git a/day08/main.cpp b/day08/main.cpp
@@ -15,7 +15,7 @@ typedef std::map<char, std::vector<Vec2>> Data;
 // I got too lazy these days
 [[ maybe_unused ]] static int sFieldSize = 0;
 
-std::vector<Vec2> calc_an(Vec2 a1, Vec2 a2) {
+std::vector<Vec2> calc_an1(Vec2 a1, Vec2 a2) {
     std::vector<Vec2> out;
     Vec2 d1(a1.first-a2.first, a1.second-a2.second);
     Vec2 d2(-d1.first, -d1.second);
@@ -30,14 +30,43 @@ std::vector<Vec2> calc_an(Vec2 a1, Vec2 a2) {
     return out;
 }
 
-std::set<Vec2> calc_antinodes(const std::vector<Vec2> &antennas) {
+std::set<Vec2> calc_antinodes1(const std::vector<Vec2> &antennas) {
     std::set<Vec2> out;
     for (auto it1=antennas.begin(); it1!=antennas.end(); it1++) {
         for (auto it2=it1+1; it2!=antennas.end(); it2++) {
-            auto [x1, y1] = *it1;
-            auto [x2, y2] = *it2;
-            std::printf("%d:%d -> %d:%d\n", x1, y1, x2, y2);
-            std::vector<Vec2> an = calc_an(*it1, *it2);
+            std::vector<Vec2> an = calc_an1(*it1, *it2);
+            for (auto &v:an) out.insert(v);
+        }
+    }
+    return out;
+}
+
+std::vector<Vec2> calc_an2(Vec2 a1, Vec2 a2) {
+    std::vector<Vec2> out;
+    out.push_back(a1);
+    out.push_back(a2);
+    Vec2 d1(a1.first-a2.first, a1.second-a2.second);
+    Vec2 d2(-d1.first, -d1.second);
+    Vec2 p1(a1.first+d1.first, a1.second+d1.second);
+    Vec2 p2(a2.first+d2.first, a2.second+d2.second);
+    while (p1.first>=0&&p1.second>=0&&p1.first<sFieldSize&&p1.second<sFieldSize) {
+        out.push_back(p1);
+        p1.first+=d1.first;
+        p1.second+=d1.second;
+    }
+    while (p2.first>=0&&p2.second>=0&&p2.first<sFieldSize&&p2.second<sFieldSize) {
+        out.push_back(p2);
+        p2.first+=d2.first;
+        p2.second+=d2.second;
+    }
+    return out;
+}
+
+std::set<Vec2> calc_antinodes2(const std::vector<Vec2> &antennas) {
+    std::set<Vec2> out;
+    for (auto it1=antennas.begin(); it1!=antennas.end(); it1++) {
+        for (auto it2=it1+1; it2!=antennas.end(); it2++) {
+            std::vector<Vec2> an = calc_an2(*it1, *it2);
             for (auto &v:an) out.insert(v);
         }
     }
@@ -69,25 +98,23 @@ T read_file(const std::string &path) {
 
 int part1(Data &input [[ maybe_unused ]]) {
     std::set<Vec2> out;
-    std::cout << std::endl;
     for (auto &[k, v] : input) {
-        std::cout << "key:" << k << std::endl;
-        for (auto &p : v) {
-            std::cout << "[" << p.first << "," << p.second << "]";
-        }
-        std::cout << std::endl;
-        std::set<Vec2> an = calc_antinodes(v);
-        std::printf("%ld antinodes:", an.size());
+        std::set<Vec2> an = calc_antinodes1(v);
         for (auto &n:an) {
-            std::printf("[%d,%d]", n.first, n.second);
             out.insert(n);
         }
-        std::cout << std::endl;
     }
     return (int)out.size();
 }
 int part2(Data &input [[ maybe_unused ]]) {
-    return 0;
+    std::set<Vec2> out;
+    for (auto &[k, v] : input) {
+        std::set<Vec2> an = calc_antinodes2(v);
+        for (auto &n:an) {
+            out.insert(n);
+        }
+    }
+    return (int)out.size();
 }
 
 int main(int argc, char **argv) {
diff --git a/day08/test2.txt b/day08/test2.txt
@@ -0,0 +1,10 @@
+T.........
+...T......
+.T........
+..........
+..........
+..........
+..........
+..........
+..........
+..........