Submission #626267

#	Time	Username	Problem	Language	Result	Execution time	Memory
626267		Eae02	Catfish Farm (IOI22_fish)	C++17	100 / 100	742 ms	76392 KiB

fish

#include "fish.h"

#include <bits/stdc++.h>
using ll = long long;
using namespace std;
#define all(x) begin(x),end(x)

struct SegTree {
	using T = ll; // use pair of value and index to get index from queries
	T f(T a, T b) { return max(a, b); }
	static constexpr T UNIT = 0; // neutral value for f
	
	vector<T> s; ll n;
	SegTree(ll len) : s(2 * len, UNIT), n(len) {}
	void set(ll pos, T val) {
		for (s[pos += n] = val; pos /= 2;)
			s[pos] = f(s[pos * 2], s[pos * 2 + 1]);
	}
	T query(ll lo, ll hi) { // query lo to hi (hi not included)
		if (lo >= hi) return UNIT;
		T ra = UNIT, rb = UNIT;
		for (lo += n, hi += n; lo < hi; lo /= 2, hi /= 2) {
			if (lo % 2) ra = f(ra, s[lo++]);
			if (hi % 2) rb = f(s[--hi], rb);
		}
		return f(ra, rb);
	}
};

vector<vector<pair<ll, ll>>> fishWeightSum;

ll weightSum(ll x, ll y) {
	if (x < 0 || x >= (ll)fishWeightSum.size())
		return 0;
	ll idx = lower_bound(all(fishWeightSum[x]), make_pair(y, (ll)-1)) - fishWeightSum[x].begin();
	if (fishWeightSum[x][idx].first > y)
		idx--;
	return fishWeightSum[x][idx].second;
}

long long max_weights(int N, int M, std::vector<int> X, std::vector<int> Y, std::vector<int> W) {
	if (M == 0) return 0;
	
	vector<pair<ll, ll>> piers; piers.reserve(M * 2);
	vector<tuple<ll, ll, ll>> fish; fish.reserve(M);
	for (ll i = 0; i < M; i++) {
		fish.emplace_back(X[i], Y[i], W[i]);
		if (X[i] != 0)
			piers.emplace_back(X[i] - 1, Y[i]);
		if (X[i] != N - 1)
			piers.emplace_back(X[i] + 1, Y[i]);
	}
	sort(all(piers));
	piers.erase(unique(all(piers)), piers.end());
	
	sort(all(fish));
	fishWeightSum.resize(N);
	for (ll i = 0; i < N; i++) {
		fishWeightSum[i].emplace_back(-1, 0);
	}
	for (auto [x, y, w] : fish) {
		fishWeightSum[x].emplace_back(y, fishWeightSum[x].back().second + w);
	}
	for (ll i = 0; i < N; i++) {
		fishWeightSum[i].emplace_back(N + 10, fishWeightSum[i].back().second);
	}
	
	SegTree st1(piers.size());
	SegTree st2(piers.size());
	SegTree st3(piers.size());
	
	vector<array<ll, 2>> dpv(piers.size() + 1);
	array<ll, 2>* dp = &dpv[1];
	for (ll lp = (ll)piers.size() - 1; lp >= -1; lp--) {
		ll cx = lp == -1 ? -5 : piers[lp].first;
		ll cy = lp == -1 ? -5 : piers[lp].second;
		
		ll x1ShorterFirstIdx = lower_bound(all(piers), make_pair(cx + 1, (ll)-1)) - piers.begin();
		ll x1LongerFirstIdx = lower_bound(all(piers), make_pair(cx + 1, cy)) - piers.begin();
		ll x2ShorterFirstIdx = lower_bound(all(piers), make_pair(cx + 2, (ll)-1)) - piers.begin();
		ll x2LongerFirstIdx = lower_bound(all(piers), make_pair(cx + 2, cy)) - piers.begin();
		ll c3FirstIdx = lower_bound(all(piers), make_pair(cx + 3, (ll)-1)) - piers.begin();
		
		ll ans = 0;
		ans = max(ans, st1.query(x1ShorterFirstIdx, x1LongerFirstIdx));
		ans = max(ans, st3.query(x2ShorterFirstIdx, x2LongerFirstIdx));
		ans = max(ans, max(st2.query(x2LongerFirstIdx, c3FirstIdx), 0LL) - weightSum(cx + 1, cy));
		ans = max(ans, st2.query(c3FirstIdx, (ll)piers.size()));
		dp[lp][0] = ans;
		ans = max(ans, max(st2.query(x1LongerFirstIdx, x2ShorterFirstIdx), 0LL) - weightSum(cx, cy) - weightSum(cx + 1, cy));
		dp[lp][1] = ans;
		
		/*
		for (ll allowNext = 0; allowNext < 2; allowNext++) {
			ll ans = 0;
			ans = max(ans, st1.query(x1ShorterFirstIdx, x1LongerFirstIdx));
			if (allowNext) {
				ans = max(ans, max(st2.query(x1LongerFirstIdx, x2ShorterFirstIdx), 0LL) - weightSum(cx, cy) - weightSum(cx + 1, cy));
			}
			
			ans = max(ans, st3.query(x2ShorterFirstIdx, x2LongerFirstIdx));
			
			ans = max(ans, max(st3.query(x2LongerFirstIdx, c3FirstIdx), 0LL) - weightSum(cx + 1, cy));
			
			ans = max(ans, st3.query(c3FirstIdx, (ll)piers.size()));
			
			dp[lp][allowNext] = ans;
		}*/
		
		if (lp != -1) {
			st1.set(lp, dp[lp][0] + weightSum(cx + 1, cy) - weightSum(cx, cy));
			st2.set(lp, dp[lp][1] + weightSum(cx + 1, cy) + weightSum(cx - 1, cy));
			st3.set(lp, dp[lp][1] + weightSum(cx + 1, cy));
		}
	}
	
	return dp[-1][1];
}

• Subtask 1: 3 / 3
• Subtask 2: 6 / 6
• Subtask 3: 9 / 9
• Subtask 4: 14 / 14
• Subtask 5: 21 / 21
• Subtask 6: 17 / 17
• Subtask 7: 14 / 14
• Subtask 8: 16 / 16