Submission #597637

#	Time	Username	Problem	Language	Result	Execution time	Memory
597637		gary4988	A Huge Tower (CEOI10_tower)	C++17	100 / 100	324 ms	8772 KiB

tower

#include <bits/stdc++.h>
using namespace std;

const int MOD = 1e9 + 9;

int main () {
    // freopen("tower.in", "r", stdin);
	int n, d;
	cin >> n >> d;
	vector<int> a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}

	sort(a.begin(), a.end()); 

	int r = n-1, l = n-1, sol = 1;   // all pointers start at right end, l move first

	for (int r = n-1; r > 0; r--) {
		while (l >= 0 && a[r] - a[l] <= d) {
            l--;
        }
        // at this point, (l, r]
		int b = r - l;
		sol = (sol * 1LL * b) % MOD;
	}
	cout << sol << '\n';
}

Compilation message (stderr)

tower.cpp: In function 'int main()':
tower.cpp:17:6: warning: unused variable 'r' [-Wunused-variable]
   17 |  int r = n-1, l = n-1, sol = 1;   // all pointers start at right end, l move first
      |      ^

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
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• Subtask 20: 5 / 5