Submission #462302

#	Time	Username	Problem	Language	Result	Execution time	Memory
462302		bigo	Fountain (eJOI20_fountain)	C++14	30 / 100	418 ms	7300 KiB

fountain

#include <bits/stdc++.h>
using namespace std;
#define ll long long
typedef pair<int, int> pii;
int main() {
	int n, q;
	cin >> n >> q;
	vector<pii>vec(n);
	ll sum = 0;
	for (int i = 0; i < n; i++) {
		cin >> vec[i].first >> vec[i].second;
		sum += vec[i].second;
	}
	n++;
	sum += 1e9;
	vec.push_back({ 1e9,1e9 });
	vector<int>sef(n+1);
	sef[n] = 0;
	for (int i = 0; i < n; i++) {
		sef[n - 1 - i] = sef[n - i] + vec[n - 1 - i].second;
	}
	vector<int>pref(n);
	pref[0] = vec[0].second;
	for (int i = 1; i < n; i++) {
		pref[i] = pref[i - 1] + vec[i].second;
	}
	vector<int>ans1;
	while (q--) {
		int r, c;
		cin >> r >> c;
		r--;
		int lo = r;
		int hi = n - 1;
		int mid;
		if (r == 0) {
			while (lo < hi) {
				mid = (lo + hi) / 2;
				if ((sum - sef[mid+1]) < c) {
					lo = mid + 1;
				}
				else if (c == (sum - sef[mid+1]))
					break;
				else {
					hi = mid;
				}
			}
			if ((sum - sef[mid + 1]) < c)
				mid++;
		}
		else {
			while (lo < hi) {
				mid = (lo + hi) / 2;
				if ((sum - pref[r - 1] - sef[mid+1]) < c) {
					lo = mid + 1;
				}
				else if (c == (sum - pref[r - 1] - sef[mid+1]))
					break;
				else {
					hi = mid;
				}
			}
			if ((sum - pref[r - 1] - sef[mid + 1]) < c)
				mid++;
		}
		if (mid == n - 1)
			mid = -1;
		ans1.push_back(mid+1);
	}
	for (int i = 0; i < ans1.size(); i++) {
		cout << ans1[i] << endl;
	}
}

Compilation message (stderr)

fountain.cpp: In function 'int main()':
fountain.cpp:69:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   69 |  for (int i = 0; i < ans1.size(); i++) {
      |                  ~~^~~~~~~~~~~~~
fountain.cpp:47:23: warning: 'mid' may be used uninitialized in this function [-Wmaybe-uninitialized]
   47 |    if ((sum - sef[mid + 1]) < c)
      |                   ~~~~^~~

• Subtask 1: 0 / 30
• Subtask 2: 30 / 30
• Subtask 3: 0 / 40