Submission #949425

#	Time	Username	Problem	Language	Result	Execution time	Memory
949425		Numberz	Distributing Candies (IOI21_candies)	C++17	100 / 100	232 ms	53332 KiB

candies

#include <bits/stdc++.h>
using namespace std;


const int n_bits = 19;
const long long inf = 1e18;
long long minseg[1 << (n_bits + 1)];
long long maxseg[1 << (n_bits + 1)];
long long lazyadd[1 << (n_bits + 1)];

//we will use lazy propogation segment tree
//must support min and max, so basically 2 put together
struct segtree {
	long long last_value = 0;
	long long small = inf;
	long long big = -inf;

	segtree() {}

	void update(int node, int change) {
		last_value += change;
		node += (1 << n_bits);
		lazyadd[node] += change;
		while (node > 1) {
			if (node % 2 == 0) {
				lazyadd[node + 1] += change;
			}
			minseg[node / 2] = min(minseg[node] + lazyadd[node], minseg[node ^ 1] + lazyadd[node ^ 1]);
			maxseg[node / 2] = max(maxseg[node] + lazyadd[node], maxseg[node ^ 1] + lazyadd[node ^ 1]);
			node /= 2;
		}
	}

	//returns largest index i such that range >= capacity
	int solve(int capacity) {
		int node = 1;
		small = inf;
		big = -inf;
		long long lz = 0;
		while (node < (1 << n_bits)) {
			lz += lazyadd[node];
			node *= 2;
			if (max(big, maxseg[node + 1] + lazyadd[node + 1] + lz) - min(small, minseg[node + 1] + lazyadd[node + 1] + lz) > capacity) {
				node++;
			}
			else {
				big = max(big, maxseg[node + 1] + lazyadd[node + 1] + lz);
				small = min(small, minseg[node + 1] + lazyadd[node + 1] + lz);
			}
		}
		if (minseg[node] + lazyadd[node] + lz < last_value) {
			return capacity - (big - last_value);
		}
		else {
			return last_value - small;
		}
	}
};

vector<pair<int, int>> toggle[(int)6e5];
//this tells you what you need to toggle on/off when moving across the boxes
//stores a pair indicating the query id and the change in the number of candies
vector<int> distribute_candies(vector<int> C, vector<int> L, vector<int> R, vector<int> V) {
	int n = C.size();
	int q = L.size();
	segtree s;

	for (int i = 0; i < q; i++) {
		toggle[L[i]].push_back({i, V[i]});
		toggle[R[i] + 1].push_back({ i, -V[i] });
	}

	vector<int> ans;
	ans.resize(n);
	for (int i = 0; i < n; i++) {
		for (auto p : toggle[i]) {
			s.update(p.first + 2, p.second);
		}

		if (maxseg[1] - minseg[1] < C[i]) {
			ans[i] = s.last_value - (minseg[1] + lazyadd[1]);
		}
		else {
			ans[i] = s.solve(C[i]);
		}
	}

	return ans;
}

• Subtask 1: 3 / 3
• Subtask 2: 8 / 8
• Subtask 3: 27 / 27
• Subtask 4: 29 / 29
• Subtask 5: 33 / 33