2024 day 9

2024/9/main-1.cpp

@@ -0,0 +1,53 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef unsigned long long ull;
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	char c;
+	deque<tuple<int, int, int>> blocks;
+	deque<tuple<int, int>> frees;
+	int i = 0, n = 0;
+	bool rfree = false;
+	while (cin >> c) {
+		c -= '0';
+		if (rfree) {
+			if (c > 0) {
+				frees.push_back({n, c});
+			}
+		} else {
+			blocks.push_back({i++, n, c});
+		}
+		rfree = !rfree;
+		n += c;
+	}
+
+	while (frees.size() > 0) {
+		auto &[bi, bx, bn] = blocks.back();
+		auto &[fx, fn] = frees[0];
+		if (fx > bx) {
+			break;
+		}
+		int nmoved = min(fn, bn);
+		bn -= nmoved;
+		fn -= nmoved;
+		blocks.push_front({bi, fx, nmoved});
+		if (fn == 0) {
+			frees.pop_front();
+		} else {
+			fx += nmoved;
+		}
+		if (bn == 0) {
+			blocks.pop_back();
+		}
+	}
+
+	ull sum = 0;
+	for (auto &[bi, bx, bn] : blocks) {
+		sum += (ull)bi * (bn * bx + bn * (bn - 1) / 2);
+	}
+	cout << sum << '\n';
+}

2024/9/main-2.cpp

@@ -0,0 +1,45 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef unsigned long long ull;
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	char c;
+	vector<tuple<int, int, int, bool>> blocks;
+	vector<tuple<int, int>> frees;
+	int i = 0, n = 0;
+	bool rfree = false;
+	while (cin >> c) {
+		c -= '0';
+		if (rfree) {
+			if (c > 0) {
+				frees.push_back({n, c});
+			}
+		} else {
+			blocks.push_back({i++, n, c, false});
+		}
+		rfree = !rfree;
+		n += c;
+	}
+
+	for (auto &[fx, fn] : frees) {
+		for (auto &[bi, bx, bn, bm] : blocks | views::reverse) {
+			if (bm || bn > fn || bx < fx) {
+				continue;
+			}
+			bx = fx;
+			bm = true;
+			fx += bn;
+			fn -= bn;
+		}
+	}
+
+	ull sum = 0;
+	for (auto &[bi, bx, bn, bm] : blocks) {
+		sum += (ull)bi * (bn * bx + bn * (bn - 1) / 2);
+	}
+	cout << sum << '\n';
+}