Submission #25399

#	Time	Username	Problem	Language	Result	Execution time	Memory
25399		khsoo01	Watching (JOI13_watching)	C++11	100 / 100	483 ms	33472 KiB

watching

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll inf = 1e18;
ll n, x[2005], a, b, na[2005], nb[2005];
ll dt[2005][2005];

bool can (ll P) {
	for(ll i=1;i<=n;i++) {
		na[i] = lower_bound(x+1, x+1+n, x[i]+P) - x - 1;
		nb[i] = lower_bound(x+1, x+1+n, x[i]+2*P) - x - 1;
		for(ll j=0;j<=i;j++) dt[i][j] = inf;
	}
	for(ll i=1;i<=n;i++) {
		for(ll j=0;j<i;j++) {
			dt[na[i]][j] = min(dt[na[i]][j], dt[i-1][j] + 1);
			dt[nb[i]][j+1] = min(dt[nb[i]][j+1], dt[i-1][j]);
		}
	}
	for(ll i=0;i<=b;i++) if(dt[n][i] <= a) return true;
	return false;
}

int main()
{
	scanf("%lld%lld%lld",&n,&a,&b);
	if(a + b >= n) {puts("1"); return 0;}
	for(ll i=1;i<=n;i++) scanf("%lld",&x[i]);
	sort(x+1, x+1+n);
	ll S = 1, E = inf;
	while(S<E) {
		ll M = (S+E)/2;
		can(M) ? E = M : S = M+1;
	}
	printf("%lld\n",S);
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:26:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld%lld%lld",&n,&a,&b);
                                ^
watching.cpp:28:42: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(ll i=1;i<=n;i++) scanf("%lld",&x[i]);
                                          ^

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