oj.uz

Submission #1088685

# Submission time Handle Problem Language Result Execution time Memory
1088685 2024-09-14T18:56:05 Z xnqs Divide and conquer (IZhO14_divide) C++17
0 / 100
 1 ms 348 KB 
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <cstring>

int x;
int diff_coords[100005];
int coords[100005];
int arr1[100005];
int arr2[100005];
int64_t pfx2[100005];
int64_t pfx3[100005];
int64_t pfx_min[100005];

int main() {
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(NULL);
	std::cout.tie(NULL);

	std::cin >> x;
	for (int i = 1; i <= x; i++) {
		int a, b, c;
		std::cin >> a >> b >> c;
		coords[i] = a;
		diff_coords[i-1] = coords[i] - coords[i-1];
		arr1[i] = c;
		arr2[i] = b;
		pfx2[i] = pfx2[i-1] + arr2[i];
	}

	pfx_min[0] = 0x3f3f3f3f3f3f3f3f;
	for (int i = 1; i <= x; i++) {
		pfx3[i] = pfx3[i-1] + arr1[i] - diff_coords[i-1];
		pfx_min[i] = std::min(pfx_min[i-1], pfx3[i]);
	}

	int64_t ans = 0;
	// case 1: individual elements
	for (int i = 1; i <= x; i++) {
		ans = std::max(ans, (int64_t)arr2[i]);
	}

	// case 2: sequences of two or more elements
	int64_t base_gold = arr2[1];
	int64_t base_diff = arr1[1];
	for (int i = 2; i <= x; i++) {
		base_gold += arr2[i];
		base_diff += arr1[i];
		base_diff -= diff_coords[i-1];

		if (base_diff>=0) {
			ans = std::max(ans, base_gold);
			continue;
		}

		int64_t gold = base_gold;
		int64_t diff = base_diff;

		// binary search for minimum position where sum is <= base_diff
		const auto bs = [&]() {
			int ret = i;
			int l = 1, r = i-1;
			while (l<=r) {
				int m = (l+r)>>1;
				if (pfx_min[m]<=base_diff) {
					ret = m;
					r = m-1;
				}
				else {
					l = m+1;
				}
			}
			return ret;
		};

		int pos = bs();
		if (pos==i) {
			continue;
		}

		gold -= pfx2[pos];
		ans = std::max(ans,gold);
	}

	std::cout << ans << "\n";
}

Compilation message

divide.cpp: In function 'int main()':
divide.cpp:62:11: warning: unused variable 'diff' [-Wunused-variable]
   62 |   int64_t diff = base_diff;
      |           ^~~~

Subtask #1
0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 348 KB Output is correct
2 Incorrect 0 ms 348 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #2
0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 348 KB Output is correct
2 Incorrect 0 ms 348 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #3
0 / 52.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 348 KB Output is correct
2 Incorrect 0 ms 348 KB Output isn't correct
3 Halted 0 ms 0 KB -