Submission #826465

#	Time	Username	Problem	Language	Result	Execution time	Memory
826465		esomer	Radio Towers (IOI22_towers)	C++17	27 / 100	4080 ms	23032 KiB

towers

#include <bits/stdc++.h>
#include "towers.h"

using namespace std;

int N, spec;
vector<int> H, lw;
vector<vector<pair<int, int>>> mn;

pair<int, int> get_mx(int l, int r){
	int k = lw[r - l + 1];
	return max(mn[k][r], mn[k][l + (1 << k) - 1]);
}

void init(int n, vector<int> H1) {
	N = n;
	H = H1;
	spec = 0;
	bool asc = 1;
	for(int i = 1; i < N; i++){
		if(spec == -1) break;
		if(H[i] > H[i-1]){
			if(asc) spec = i;
			else spec = -1;
		}else{
			asc = 0;
		}
	}
	lw.resize(N+1);
	mn.assign(20, vector<pair<int, int>>(N));
	for(int k = 0; k < 20; k++){
		for(int i = 0; i < N; i++){
			if(k == 0) mn[k][i] = {H[i], i};
			else{
				if(i - (1 << (k-1)) < 0) mn[k][i] = mn[k-1][i];
				else{
					mn[k][i] = max(mn[k-1][i], mn[k-1][i - (1 << (k-1))]);
				}
			}
		}
	}
	int pw = 0;
	int curr = 2;
	for(int i = 1; i <= N; i++){
		if(i == curr){
			pw++; curr *= 2;
		}
		lw[i] = pw;
	}
}

pair<int, int> dnc(int L, int R, int D) {
	if(L == R) {
		return {H[L], 1};
	}else if(L > R){
		return {2e9, 0};
	}
	pair<int, int> pr = get_mx(L, R);
	int mx = pr.first;
	int ind = pr.second;
	pair<int, int> ans1 = dnc(ind + 1, R, D);
	pair<int, int> ans2 = dnc(L, ind - 1, D);
	if(ans1.first <= mx - D && ans2.first <= mx - D) return {ans1.first, ans1.second + ans2.second};
	else return min(ans1, ans2);
}

int max_towers(int L, int R, int D) {
	if(spec == -1) return dnc(L, R, D).second;
	else{
		int ans = 1;
		if(L < spec && R > spec && H[L] <= H[spec] - D && H[R] <= H[spec] - D) ans++;
		return ans;
	}
}

// int main() {
//   int N, Q;
//   assert(2 == scanf("%d %d", &N, &Q));
//   std::vector<int> H(N);
//   for (int i = 0; i < N; ++i) {
//     assert(1 == scanf("%d", &H[i]));
//   }
//   init(N, H);
//   for (int i = 0; i < Q; ++i) {
//     int L, R, D;
//     assert(3 == scanf("%d %d %d", &L, &R, &D));
//     printf("%d\n", max_towers(L, R, D));
//   }
//   return 0;
// }

• Subtask 1: 4 / 4
• Subtask 2: 11 / 11
• Subtask 3: 12 / 12
• Subtask 4: 0 / 14
• Subtask 5: 0 / 17
• Subtask 6: 0 / 19
• Subtask 7: 0 / 23