oj.uz

Submission #239500

# Submission time Handle Problem Language Result Execution time Memory
239500 2020-06-16T01:00:45 Z frodakcin Watching (JOI13_watching) C++11
100 / 100
 109 ms 16248 KB 
#include <cstdio>
#include <cstring>
#include <algorithm>

template<typename T> bool ckmax(T& a, T b){return a<b?a=b,1:0;}
template<typename T> bool ckmin(T& a, T b){return a>b?a=b,1:0;}

const int MN = 2e3+10;
int N, P, Q, dp[MN][MN], a[MN], nex[MN][2];

bool test(int w)
{
	nex[N][0] = nex[N][1] = 0;
	for(int i=0;i<N;++i)//can be optimized from O(N log N) to O(N) but it isnt bottleneck
	{
		nex[i][0] = std::lower_bound(a, a+N, a[i]+w  )-a;
		nex[i][1] = std::lower_bound(a, a+N, a[i]+w*2)-a;
	}
	memset(dp, -1, sizeof dp);
	dp[0][0]=0;
	for(int i=0;i<=P;++i)
		for(int j=0;j<=Q;++j)
			if(~dp[i][j])
			{
				int x=dp[i][j];
				if(x==N) return 1;
				if(i<P) ckmax(dp[i+1][j], nex[x][0]);
				if(j<Q) ckmax(dp[i][j+1], nex[x][1]);
			}
	return 0;
}
int main()
{
	scanf("%d%d%d", &N, &P, &Q);
	for(int i=0;i<N;++i) scanf("%d", a+i);
	std::sort(a, a+N);
	if(P+Q>=N) return printf("1\n"),0;
	int l=0,r=1e9,m;
	for(;r-l>1;)
	{
		m=l+(r-l)/2;
		if(test(m))
			r=m;
		else
			l=m;
	}
	printf("%d\n", r);
	return 0;
}

Compilation message

watching.cpp: In function 'int main()':
watching.cpp:34:7: 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:35:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=0;i<N;++i) scanf("%d", a+i);
                       ~~~~~^~~~~~~~~~~

Subtask #1
50.0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 67 ms 16128 KB Output is correct
2 Correct 4 ms 256 KB Output is correct
3 Correct 68 ms 16128 KB Output is correct
4 Correct 5 ms 256 KB Output is correct
5 Correct 4 ms 256 KB Output is correct
6 Correct 4 ms 384 KB Output is correct
7 Correct 67 ms 16128 KB Output is correct
8 Correct 65 ms 16000 KB Output is correct
9 Correct 84 ms 16128 KB Output is correct
10 Correct 65 ms 16128 KB Output is correct
11 Correct 74 ms 16248 KB Output is correct
12 Correct 67 ms 16128 KB Output is correct
13 Correct 67 ms 16128 KB Output is correct
14 Correct 65 ms 16128 KB Output is correct
15 Correct 67 ms 16128 KB Output is correct

Subtask #2
50.0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 73 ms 16128 KB Output is correct
2 Correct 4 ms 256 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 5 ms 384 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Correct 72 ms 16128 KB Output is correct
8 Correct 78 ms 16128 KB Output is correct
9 Correct 76 ms 16128 KB Output is correct
10 Correct 81 ms 16128 KB Output is correct
11 Correct 74 ms 16128 KB Output is correct
12 Correct 109 ms 16128 KB Output is correct
13 Correct 73 ms 16128 KB Output is correct
14 Correct 72 ms 16128 KB Output is correct
15 Correct 73 ms 16128 KB Output is correct