Submission #25397

#	Time	Username	Problem	Language	Result	Execution time	Memory
25397		kdh9949	Watching (JOI13_watching)	C++14	100 / 100	76 ms	17824 KiB

watching

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

int n, p, q, a[2010], nx[2][2010], dp[2010][2010];

int can(int x){
	for(int i = 1; i <= n; i++){
		nx[0][i] = (int)(upper_bound(a + 1, a + n + 1, (int)(a[i] + x - 1)) - a - 1);
		nx[1][i] = (int)(upper_bound(a + 1, a + n + 1, (int)(a[i] + 2LL * x - 1)) - a - 1);
	}
	for(int i = 0; i <= p; i++){
		for(int j = !i; j <= q; j++){
			dp[i][j] = 0;
			if(i) dp[i][j] = max(dp[i][j], nx[0][dp[i - 1][j] + 1]);
			if(j) dp[i][j] = max(dp[i][j], nx[1][dp[i][j - 1] + 1]);
			if(dp[i][j] == n) return 1;
		}
	}
	return 0;
}

int main(){
	scanf("%d%d%d", &n, &p, &q);
	if(p + q >= n){ puts("1"); return 0; }
	for(int i = 1; i <= n; i++) scanf("%d", a + i);
	sort(a + 1, a + n + 1);
	int s = 1, e = 1e9 + 1;
	while(s <= e){
		int m = (s + e) / 2;
		if(can(m)) e = m - 1;
		else s = m + 1;
	}
	printf("%d\n", s);
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:23:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d", &n, &p, &q);
                             ^
watching.cpp:25:48: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i = 1; i <= n; i++) scanf("%d", a + i);
                                                ^

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50