Day 6

Author: tmoux

AdventOfCode23.cabal

@@ -78,3 +78,8 @@ executable Day4
  import: warnings, dependencies
  main-is: Main.hs
  hs-source-dirs: Day4
+
+executable Day6
+ import: warnings, dependencies
+ main-is: Main.hs
+ hs-source-dirs: Day6

Day6/Main.hs

@@ -0,0 +1,33 @@
+module Main where
+
+import Data.Tuple.Extra (both)
+
+-- Count the number of integer points x where (t - x) * x > d.
+getRoots :: Int -> Int -> Int
+getRoots t d =
+ if disc <= 0
+ then 0
+ else max 0 (r - l + 1)
+ where
+ disc :: Double
+ disc = fromIntegral (t * t - 4 * d)
+ l = ceil' ((fromIntegral t - sqrt disc) / 2.0)
+ r = floor' ((fromIntegral t + sqrt disc) / 2.0)
+ isInt x = x == fromInteger (round x)
+ ceil' x = ceiling x + if isInt x then 1 else 0
+ floor' x = floor x + if isInt x then -1 else 0
+
+part1 :: [(Int, Int)] -> Int
+part1 = product . map (uncurry getRoots)
+
+part2 :: (Int, Int) -> Int
+part2 = uncurry getRoots
+
+main :: IO ()
+main = do
+ times <- drop 1 . words <$> getLine
+ distances <- drop 1 . words <$> getLine
+ let part1Input = uncurry zip (both (map read) (times, distances))
+ part2Input = both (read . concat) (times, distances)
+ putStrLn $ "Part 1: " ++ show (part1 part1Input)
+ putStrLn $ "Part 2: " ++ show (part2 part2Input)

Day6/Makefile

@@ -0,0 +1,16 @@
+CC = g++-13
+CFLAGS = -O2 -std=c++20 -Wall
+
+all: sol
+
+sol: sol.cpp
+$(CC) $(CFLAGS) -o sol sol.cpp
+
+gen: gen.cpp
+$(CC) $(CFLAGS) -o gen gen.cpp
+
+brute: brute.cpp
+$(CC) $(CFLAGS) -o brute brute.cpp
+
+clean:
+$(RM) sol gen brute

Day6/old.cpp

@@ -0,0 +1,79 @@
+#include <bits/stdc++.h>
+using namespace std;
+using ll = long long;
+
+// Template
+#define REP(n) for (int _=0; _<(n); _++)
+#define FOR(i, a, b) for (int i=a; i<(b); i++)
+#define F0R(i, a) for (int i=0; i<(a); i++)
+#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
+#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
+ 
+#define sz(x) (int)(x).size()
+#define all(x) x.begin(), x.end()
+ 
+template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
+template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
+
+namespace std {
+ template<class Fun>
+ class y_combinator_result {
+ Fun fun_;
+ public:
+ template<class T>
+ explicit y_combinator_result(T &&fun): fun_(std::forward<T>(fun)) {}
+ 
+ template<class ...Args>
+ decltype(auto) operator()(Args &&...args) {
+ return fun_(std::ref(*this), std::forward<Args>(args)...);
+ }
+ };
+ 
+ template<class Fun>
+ decltype(auto) y_combinator(Fun &&fun) {
+ return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun));
+ }
+} // namespace std
+
+#define DEBUG(x) cerr << #x << ": " << x << '\n'
+template<typename A, typename B> 
+ostream& operator<<(ostream &os, const pair<A, B> &p) { 
+ return os << '(' << p.first << ", " << p.second << ')'; 
+}
+template<typename T_container, 
+ typename T = typename enable_if<!is_same<T_container, string>::value, 
+ typename T_container::value_type>::type> 
+ostream& operator<<(ostream &os, const T_container &v) { 
+ os << '['; string sep; 
+ for (const T &x : v) 
+ os << sep << x, sep = ", "; 
+ return os << ']'; 
+}
+mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
+
+int main() {
+ ios_base::sync_with_stdio(false); cin.tie(NULL);
+ int N = 4;
+ string t;
+ vector<int> times(N), dist(N);
+ cin >> t;
+ F0R(i, 4) cin >> times[i];
+ cin >> t;
+ F0R(i, 4) cin >> dist[i];
+
+ ll ans = 1;
+ F0R(i, N) {
+ int T = times[i];
+ int record = dist[i];
+
+ int ways = 0;
+ for (int x = 0; x <= T; x++) {
+ int d = (T - x) * x;
+ if (d > record) ways++;
+ }
+ DEBUG(ways);
+
+ ans *= ways;
+ }
+ cout << ans << '\n';
+}

Day6/sol.cpp

@@ -0,0 +1,97 @@
+#include <bits/stdc++.h>
+using namespace std;
+using ll = long long;
+
+// Template
+#define REP(n) for (int _=0; _<(n); _++)
+#define FOR(i, a, b) for (int i=a; i<(b); i++)
+#define F0R(i, a) for (int i=0; i<(a); i++)
+#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
+#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
+ 
+#define sz(x) (int)(x).size()
+#define all(x) x.begin(), x.end()
+ 
+template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
+template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
+
+namespace std {
+ template<class Fun>
+ class y_combinator_result {
+ Fun fun_;
+ public:
+ template<class T>
+ explicit y_combinator_result(T &&fun): fun_(std::forward<T>(fun)) {}
+ 
+ template<class ...Args>
+ decltype(auto) operator()(Args &&...args) {
+ return fun_(std::ref(*this), std::forward<Args>(args)...);
+ }
+ };
+ 
+ template<class Fun>
+ decltype(auto) y_combinator(Fun &&fun) {
+ return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun));
+ }
+} // namespace std
+
+#define DEBUG(x) cerr << #x << ": " << x << '\n'
+template<typename A, typename B> 
+ostream& operator<<(ostream &os, const pair<A, B> &p) { 
+ return os << '(' << p.first << ", " << p.second << ')'; 
+}
+template<typename T_container, 
+ typename T = typename enable_if<!is_same<T_container, string>::value, 
+ typename T_container::value_type>::type> 
+ostream& operator<<(ostream &os, const T_container &v) { 
+ os << '['; string sep; 
+ for (const T &x : v) 
+ os << sep << x, sep = ", "; 
+ return os << ']'; 
+}
+mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
+
+int main() {
+ ios_base::sync_with_stdio(false); cin.tie(NULL);
+ int N = 4;
+ string t;
+ vector<int> times(N), dist(N);
+ cin >> t;
+ string TIME;
+ F0R(i, 4) {
+ cin >> t;
+ TIME += t;
+ }
+
+ string DIST;
+ cin >> t;
+ F0R(i, 4) {
+ cin >> t;
+ DIST += t;
+ }
+
+ ll my_time, my_dist;
+ {
+ stringstream ss(TIME);
+ ss >> my_time;
+ }
+ {
+ stringstream ss(DIST);
+ ss >> my_dist;
+ }
+
+ DEBUG(my_time);
+ DEBUG(my_dist);
+
+ int ways = 0;
+ vector<ll> v;
+ for (int x = 0; x <= my_time; x++) {
+ ll d = (my_time - x) * x;
+ if (d > my_dist) {
+ v.push_back(x);
+ ways++;
+ }
+ }
+ DEBUG(ways);
+ cout << v.front() << ' ' << v.back() << endl;
+}