commit d9fbaa155185220ee141f75d764890983ef35ca2
parent ec95deb6f565d7994876932834489e7a22e19e11
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date: Sat, 14 Dec 2024 08:38:52 +0100
Day 14 2024 (I did not like this one)
Diffstat:
5 files changed, 153 insertions(+), 0 deletions(-)
diff --git a/2024/14/Makefile b/2024/14/Makefile
@@ -0,0 +1,24 @@
+CC=g++ -std=c++20 -g -Wall
+
+a:
+ ${CC} -o a.out day14a.cpp
+
+b:
+ ${CC} -o b.out day14b.cpp
+
+clean:
+ rm -f a b
+
+atest: a
+ ./a.out
+
+btest: b
+ ./b.out
+
+arun: a
+ ./a.out < input
+
+brun: b
+ ./b.out < input
+
+.PHONY: a b clean atest btest arun brun
diff --git a/2024/14/clean.sh b/2024/14/clean.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+sed 's/p=//; s/v=//; s/,/ /g'
diff --git a/2024/14/day14a.cpp b/2024/14/day14a.cpp
@@ -0,0 +1,40 @@
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <map>
+#include <ranges>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+#define N 101
+#define M 103
+#define T 100
+
+int quadrant(pair<int64_t, int64_t> p) {
+ if (p.first < N/2 && p.second < M/2)
+ return 1;
+ if (p.first < N/2 && p.second > M/2)
+ return 2;
+ if (p.first > N/2 && p.second < M/2)
+ return 3;
+ if (p.first > N/2 && p.second > M/2)
+ return 4;
+ return 0;
+}
+
+int main() {
+ string line;
+ int64_t p1, p2, v1, v2, q[5] = {0};
+ while (cin >> p1 >> p2 >> v1 >> v2) {
+ pair<int64_t, int64_t> final((p1 + T*(v1+N)) % N, (p2 + T*(v2+M)) % M);
+ q[quadrant(final)]++;
+ }
+
+ cout << q[1] * q[2] * q[3] * q[4] << endl;
+
+ return 0;
+}
diff --git a/2024/14/day14b.cpp b/2024/14/day14b.cpp
@@ -0,0 +1,85 @@
+/*
+I ran the simulation at 1FPS for a few minutes, staring at the screen and
+hoping to see a Christmas tree, without luck. But I noticed that the robots
+formed a strange "vertical" pattern every 103 timesteps, starting at t=30,
+and a strange "horizontal" pattern every 101 timesteps, starting at t=81.
+So I solved the diophantine equation 30+103y = 81+101x, and the smallest
+solution (y=76, x=77) gave the correct answer t=30+103*76=7858
+*/
+
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <map>
+#include <ranges>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <unistd.h>
+#include <vector>
+using namespace std;
+
+#define N 101
+#define M 103
+#define T 100
+
+char board[N][M];
+
+struct Robot {
+ pair<int64_t, int64_t> p, v;
+ Robot(int64_t p1, int64_t p2, int64_t v1, int64_t v2) : p(p1, p2), v(v1, v2) {}
+};
+
+int quadrant(pair<int64_t, int64_t> p) {
+ if (p.first < N/2 && p.second < M/2)
+ return 1;
+ if (p.first < N/2 && p.second > M/2)
+ return 2;
+ if (p.first > N/2 && p.second < M/2)
+ return 3;
+ if (p.first > N/2 && p.second > M/2)
+ return 4;
+ return 0;
+}
+
+pair<int64_t, int64_t> pos(Robot r, int64_t t) {
+ return make_pair((r.p.first + t*(r.v.first+N))%N,
+ (r.p.second + t*(r.v.second+M))%M);
+}
+
+void visualize(vector<Robot>& robots, int64_t t) {
+ for (int i = 0; i < N; i++)
+ for (int j = 0; j < M; j++)
+ board[i][j] = ' ';
+ for (const auto& r : robots) {
+ auto [x,y] = pos(r, t);
+ board[x][y] = '*';
+ }
+ for (int i = 0; i < N; i++) {
+ for (int j = 0; j < M; j++)
+ cout << board[i][j];
+ cout << endl;
+ }
+ cout << endl;
+}
+
+int main() {
+ string line;
+ int64_t p1, p2, v1, v2, q[5] = {0};
+ vector<Robot> r;
+ while (cin >> p1 >> p2 >> v1 >> v2)
+ r.push_back(Robot(p1, p2, v1, v2));
+
+
+ /* Starts at the solution */
+ for (int64_t t = 7858; ; t++) {
+ cout << "visualization of time " << t << ": " << endl;
+ sleep(1);
+ visualize(r, t);
+ }
+
+ cout << q[1] * q[2] * q[3] * q[4] << endl;
+
+ return 0;
+}
diff --git a/2024/template.cpp b/2024/template.cpp
@@ -1,4 +1,5 @@
#include <algorithm>
+#include <cstdint>
#include <iostream>
#include <map>
#include <ranges>
