Submission #1046616

#	Time	Username	Problem	Language	Result	Execution time	Memory
1046616		GusterGoose27	Mizuyokan 2 (JOI23_mizuyokan2)	C++17	60 / 100	241 ms	166420 KiB

mizuyokan2

#include <bits/stdc++.h>

using namespace std;

const int MAXN = 25e4+5;
const int MAXB = 18;
int arr[MAXN];
int Arr[MAXN];
typedef long long ll;
ll pre[MAXN];
int n, q;

ll sum(int l, int r) {
	return pre[r+1] - pre[l];
}

int dp[MAXN];
vector<int> to_activate[MAXN];

typedef array<int, 2> ar2;
ar2 nxt[MAXN][MAXB];
int sjump[MAXN][MAXB];
int spos[MAXN];

int tmx[2*MAXN];

void reset() {
	fill(tmx, tmx+2*n+2, -1);
}

void upd(int p, int v) {
	p += n+1;
	tmx[p] = max(tmx[p], v);
	for (p /= 2; p > 0; p /= 2) {
		tmx[p] = max(tmx[2*p], tmx[2*p+1]);
	}
}

int get_mx(int l, int r) {
	l += n+1;
	r += n+2;
	int ans = -1;
	for (; r > l; l /= 2, r /= 2) {
		if (l & 1) ans = max(ans, tmx[l++]);
		if (r & 1) ans = max(ans, tmx[--r]);
	}
	return ans;
}

ll vpre(int v) {
	return arr[v] + pre[v+1];
}

int lift(int l, int r, int cur = -1) {
	if (cur == -1) return max(lift(l, r, l), 1+lift(l, r, spos[l]));
	if (cur >= r) return -1;
	if (nxt[cur][0][0] >= r) {
		for (int i = MAXB-1; i >= 0; i--) {
			if (sjump[cur][i] < r) return lift(l, r, sjump[cur][i]);
		}
	}
	else {
		for (int i = MAXB-1; i >= 0; i--) {
			if (nxt[cur][i][0] < r) return lift(l, r, nxt[cur][i][0]) + nxt[cur][i][1];
		}
	}
	if (sum(cur+1, r-1) > arr[cur]) return 2;
	return 1;
}

void solve_reg() {
	vector<int> stck;
	set<int> active;
	// to_activate[n-1].push_back(n);
	active.insert(n);
	nxt[n][0] = {n, 0};
	sjump[n][0] = n;
	for (int i = n-1; i >= 0; i--) {
		nxt[i][0] = {n, 0};
		sjump[i][0] = n;
		while (!stck.empty() && vpre(i) <= vpre(stck.back())) stck.pop_back();
		// if (stck.empty()) {
		if (sum(i+1, n-1) > arr[i]) {
			int mn = i+1, mx = n;
			while (mx > mn+1) {
				int mid = (mn+mx)/2;
				if (sum(i+1, mid-1) > arr[i]) mx = mid;
				else mn = mid;
			}
			nxt[i][0] = {*active.lower_bound(mx), 2};
		}
		if (!stck.empty()) {
			ar2 alt = nxt[stck.back()][0];
			if (alt[0] < nxt[i][0][0]) nxt[i][0] = alt;
			sjump[i][0] = stck.back();
		}
		stck.push_back(i);
		if (sum(0, i-1) > arr[i]) {
			int mn = -1;
			int mx = i-1;
			while (mx > mn+1) {
				int mid = (mn+mx)/2;
				if (sum(mid+1, i-1) > arr[i]) mn = mid;
				else mx = mid;
			}
			to_activate[mx].push_back(i);
		}
		for (int v: to_activate[i]) {
			active.insert(v);
		}
		spos[i] = *active.begin();
	}
	for (int j = 1; j < MAXB; j++) {
		for (int i = 0; i <= n; i++) {
			nxt[i][j] = {nxt[nxt[i][j-1][0]][j-1][0], nxt[i][j-1][1] + nxt[nxt[i][j-1][0]][j-1][1]};
			sjump[i][j] = sjump[sjump[i][j-1]][j-1];
		}
	}
	while (q--) {
		int x, y, l, r;
		cin >> x >> y >> l >> r;
		assert(arr[x-1] == y);
		cout << lift(l, r) << '\n';
	}
} 

int solve() {
	reset();
	for (int i = 0; i < n; i++) to_activate[i].clear();
	pre[0] = 0;
	for (int i = 0; i < n; i++) pre[i+1] = pre[i] + arr[i];
	dp[n] = 0;
	to_activate[n-1].push_back(n);
	vector<int> fin_activate;
	for (int i = n-1; i >= 0; i--) {
		for (int v: to_activate[i]) {
			upd(v, dp[v]);
		}
		if (i == n-1) {
			dp[i] = 1;
		}
		else {
			if (sum(i+1, n-1) <= arr[i]) dp[i] = -1;
			else {
				int mn = i+1, mx = n;
				while (mx > mn+1) {
					int mid = (mn+mx)/2;
					if (sum(i+1, mid-1) > arr[i]) mx = mid;
					else mn = mid;
				}
				dp[i] = 2+get_mx(mx, n);
				assert(dp[i] >= 2);
			}
		}
		if (sum(0, i-1) > arr[i]) {
			int mn = -1;
			int mx = i-1;
			while (mx > mn+1) {
				int mid = (mn+mx)/2;
				if (sum(mid+1, i-1) > arr[i]) mn = mid;
				else mx = mid;
			}
			if (mn == -1) fin_activate.push_back(i);
			else to_activate[mn].push_back(i);
		}
	}
	for (int v: fin_activate) {
		upd(v, dp[v]);
	}
	return max(dp[0], 1+get_mx(1, n));
}

void solve_spec() {
	int N = n;
	for (int i = 0; i < N; i++) Arr[i] = arr[i];
	while (q--) {
		int x, y, l, r;
		cin >> x >> y >> l >> r;
		Arr[x-1] = y;
		vector<int> cur;
		for (int i = l; i < r; i++) arr[i-l] = Arr[i];
		n = r-l;
		cout << solve() << '\n';
	}
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(NULL);
	cin >> n;
	pre[0] = 0;
	for (int i = 0; i < n; i++) {
		cin >> arr[i];
		pre[i+1] = pre[i] + arr[i];
	}
	// implement a mon stack to keep track of next smaller. we want to track value + prefix
	cin >> q;
	if (q <= 10) solve_spec();
	else solve_reg();
}

• Subtask 1: 6 / 6
• Subtask 2: 9 / 9
• Subtask 3: 13 / 13
• Subtask 4: 32 / 32
• Subtask 5: 0 / 29
• Subtask 6: 0 / 11