oj.uz

Submission #359268

# Submission time Handle Problem Language Result Execution time Memory
359268 2021-01-26T14:43:10 Z pure_mem Watching (JOI13_watching) C++14
100 / 100
 795 ms 16256 KB 
#include <bits/stdc++.h>

#define X first
#define Y second
#define MP make_pair
#define ll long long

using namespace std;

const int N = 2e3 + 3;

int n, p, q, a[N], dp[N][N], nx1[N], nx2[N];
queue< pair<int, int> > ord;

bool check(int lk){
	if(p + q >= n)
		return 1;
	memset(dp, -1, sizeof(dp));
	for(int i = 1;i <= n;i++){
		nx1[i] = upper_bound(a + i, a + n + 1, a[i] + lk - 1) - a - 1;
		nx2[i] = upper_bound(a + i, a + n + 1, a[i] + lk + lk - 1) - a - 1;
	}
	dp[0][0] = 0; 
	ord.push(MP(0, 0));
	bool good = 0;
	while(!ord.empty()){
		int x = ord.front().X, y = ord.front().Y;
		ord.pop();
		if(x - 1 >= 0)
			dp[x][y] = max(dp[x][y], nx1[dp[x - 1][y] + 1]);
		if(y - 1 >= 0)
			dp[x][y] = max(dp[x][y], nx2[dp[x][y - 1] + 1]);
		if(x + 1 <= p){
			if(dp[x + 1][y] == -1)
				ord.push(MP(x + 1, y));
			dp[x + 1][y] = max(dp[x + 1][y], dp[x][y]);
		}
		if(y + 1 <= q){
			if(dp[x][y + 1] == -1)
				ord.push(MP(x, y + 1));
			dp[x][y + 1] = max(dp[x][y + 1], dp[x][y]);
		}
		good |= dp[x][y] == n;
	}
	return good;	
}

int main () {		
	scanf("%d %d %d", &n, &p, &q);
	p = min(p, n), q = min(q, n);
	for(int i = 1;i <= n;i++)
		scanf("%d", a + i);
	sort(a + 1, a + n + 1);
	int tl = 1, tr = 1000000000, tp = 1000000000;
	while(tl <= tr){
		int tm = (tl + tr) / 2;
		//cerr << tm << " " << check(tm) << "\n";
		if(check(tm))
			tr = tm - 1, tp = tm;
		else
			tl = tm + 1;
	}
	printf("%d", tp);
}

Compilation message

watching.cpp: In function 'int main()':
watching.cpp:49:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   49 |  scanf("%d %d %d", &n, &p, &q);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:52:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   52 |   scanf("%d", a + i);
      |   ~~~~~^~~~~~~~~~~~~

Subtask #1
50.0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 69 ms 15980 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 69 ms 15980 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 364 KB Output is correct
6 Correct 1 ms 364 KB Output is correct
7 Correct 69 ms 15980 KB Output is correct
8 Correct 67 ms 15980 KB Output is correct
9 Correct 72 ms 15980 KB Output is correct
10 Correct 71 ms 16108 KB Output is correct
11 Correct 72 ms 15980 KB Output is correct
12 Correct 71 ms 15980 KB Output is correct
13 Correct 69 ms 15980 KB Output is correct
14 Correct 68 ms 15980 KB Output is correct
15 Correct 69 ms 15980 KB Output is correct

Subtask #2
50.0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 74 ms 16236 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 364 KB Output is correct
6 Correct 1 ms 364 KB Output is correct
7 Correct 74 ms 16108 KB Output is correct
8 Correct 144 ms 16236 KB Output is correct
9 Correct 144 ms 16108 KB Output is correct
10 Correct 203 ms 16108 KB Output is correct
11 Correct 200 ms 16256 KB Output is correct
12 Correct 795 ms 16124 KB Output is correct
13 Correct 73 ms 16108 KB Output is correct
14 Correct 74 ms 16108 KB Output is correct
15 Correct 71 ms 16236 KB Output is correct