Submission #534305

#	Time	Username	Problem	Language	Result	Execution time	Memory
534305		ac2hu	Untitled (POI11_tem)	C++17	50 / 100	475 ms	47024 KiB

Main

#include <bits/stdc++.h>
#ifdef DEBUG
#include "../templates/debug.h"
#else 
#define deb(x...)
#endif
using namespace std;
template<typename T> struct rmq {
	vector<T> v; int n;
	static const int b = 30; // block size
	vector<int> mask, t; // mask and sparse table

	int op(int x, int y) {
		return v[x] > v[y] ? x : y;
	}
	// least significant set bit
	int lsb(int x) {
		return x & -x;
	}
	// index of the most significant set bit
	int msb_index(int x) {
		return __builtin_clz(1)-__builtin_clz(x);
	}
	// answer query of v[r-size+1..r] using the masks, given size <= b
	int small(int r, int size = b) {
		// get only 'size' least significant bits of the mask
		// and then get the index of the msb of that
		int dist_from_r = msb_index(mask[r] & ((1<<size)-1));

		return r - dist_from_r;
	}
	rmq(const vector<T>& v_) : v(v_), n(v.size()), mask(n), t(n) {
		int curr_mask = 0;
		for (int i = 0; i < n; i++) {

			// shift mask by 1, keeping only the 'b' least significant bits
			curr_mask = (curr_mask<<1) & ((1<<b)-1);

			while (curr_mask > 0 and op(i, i - msb_index(lsb(curr_mask))) == i) {
				// current value is smaller than the value represented by the
				// last 1 in curr_mask, so we need to turn off that bit
				curr_mask ^= lsb(curr_mask);
			}
			// append extra 1 to the mask
			curr_mask |= 1;

			mask[i] = curr_mask;
		}

		// build sparse table over the n/b blocks
		// the sparse table is linearized, so what would be at
		// table[j][i] is stored in table[(n/b)*j + i]
		for (int i = 0; i < n/b; i++) t[i] = small(b*i+b-1);
		for (int j = 1; (1<<j) <= n/b; j++) for (int i = 0; i+(1<<j) <= n/b; i++)
			t[n/b*j+i] = op(t[n/b*(j-1)+i], t[n/b*(j-1)+i+(1<<(j-1))]);
	}
	// query(l, r) returns the actual minimum of v[l..r]
	// to get the index, just change the first and last lines of the function
	T query(int l, int r) {
		// query too small
		if (r-l+1 <= b) return v[small(r, r-l+1)];

		// get the minimum of the endpoints
		// (there is no problem if the ranges overlap with the sparse table query)
		int ans = op(small(l+b-1), small(r));

		// 'x' and 'y' are the blocks we need to query over
		int x = l/b+1, y = r/b-1;

		if (x <= y) {
			int j = msb_index(y-x+1);
			ans = op(ans, op(t[n/b*j+x], t[n/b*j+y-(1<<j)+1]));
		}

		return v[ans];
	}
};
signed main() {
	iostream::sync_with_stdio(false);
	cin.tie(nullptr);cout.tie(nullptr);
	int n;cin >> n;
	vector<pair<int,int>> a(n);
	for(auto &e : a)cin >> e.first >> e.second;
	vector<int> temp(n);
	for(int i = 0;i<n;i++)
		temp[i] = a[i].first;
	rmq rq(temp);
	// rq.init(temp);
	vector<int> leftmost(n);
	for(int i =0;i<n;i++){
		int l = 0,r = i;
		while(l < r){
			int mid = (l + r)/2;
			if(rq.query(mid,i) <= a[i].second)
				r = mid;
			else
				l = mid + 1;
		}
		leftmost[i] = l;
	}
	for(int i = 1;i<leftmost.size();i++)
		leftmost[i] = max(leftmost[i], leftmost[i - 1]);
	for(int i = 0;i<n;i++)
		leftmost[i] = i - leftmost[i] + 1;
	deb(leftmost);
	cout << *max_element(leftmost.begin(),leftmost.end());
}

Compilation message (stderr)

tem.cpp: In function 'int main()':
tem.cpp:101:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |  for(int i = 1;i<leftmost.size();i++)
      |                ~^~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 8 / 8
• Subtask 3: 8 / 8
• Subtask 4: 8 / 8
• Subtask 5: 0 / 8
• Subtask 6: 0 / 8
• Subtask 7: 0 / 8
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• Subtask 9: 9 / 9
• Subtask 10: 9 / 9
• Subtask 11: 0 / 9
• Subtask 12: 0 / 9