Submission #1332523

#TimeUsernameProblemLanguageResultExecution timeMemory
1332523madamadam3Packing Biscuits (IOI20_biscuits)C++20
33 / 100
1158 ms1904088 KiB
#include "biscuits.h"
#include <bits/stdc++.h>

using namespace std;
#define int long long int
#define cout cerr
#define trace(x) for (auto &el : x) cout << el << " "
using vi = vector<int>;
using vvi = vector<vi>;

int k = 60;

int brute(int x, vi a) {
	int ans = 0;
	int mx = 0; for (int i = 0; i < k; i++) mx += a[i]*(1LL<<i);

	for (int i = 0; i <= mx; i++) {
		vi avail = a; bool good = true;
		for (int bit = 0; bit < k; bit++) {
			if ((1LL<<bit) > i) break;
			bool use = i & 1LL<<bit;
			if (use && avail[bit] < x) good = false;

			int rem = use ? avail[bit] - x : avail[bit];
			avail[bit+1] += rem / 2;
		}

		if (good) {
			ans++;
			// cout << i << " ";
		}
	}
	// cout << "\n";
	return ans;
}

// start by pushing everything upstream, with limit x
// now the difference between using bit i or pushing it up to i+1

int count_tastiness(int x, vi a) {
	while (a.size() <= k) a.push_back(0);
	for (int i = 0; i < k; i++) {
		if (a[i] <= x+1) continue;
		a[i+1] += (a[i]-x) / 2;
		a[i] -= 2 * ((a[i]-x) / 2);
	}

	vvi dp(k+1, vi(x+1));
	dp[60][0] = 1; // 0 in each
	for (int bit = 59; bit >= 0; bit--) {
		for (int carry = 0; carry <= x; carry++) {
			dp[bit][carry] += dp[bit+1][(a[bit] + carry) / 2];
			if (a[bit] + carry >= x) dp[bit][carry] += dp[bit+1][(a[bit] + carry - x) / 2];
		}
	}

	// map<pair<int, int>, int> memo;
	// auto dfs = [&](auto &&self, int carry, int bit)->int {
	// 	if (bit >= 60 && carry == 0) return 1; // 0 in each
	// 	if (memo.count({carry, bit})) return memo[{carry, bit}];

	// 	int ans = self(self, (a[bit] + carry) / 2, bit + 1); // don't set bit
	// 	if (a[bit] + carry >= x) ans += self(self, (a[bit] + carry -x) / 2, bit+1); // set bit if possible;
	// 	return memo[{carry, bit}] = ans;
	// 	return ans;
	// };

	// int ex = brute(x, a);
	// cout << "BRUTE: " << ex << " DP: " << dp[0][0] << "\n";
	return dp[0][0];
	// return 0;
}

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