Submission #34576

#	Time	Username	Problem	Language	Result	Execution time	Memory
34576		sinhriv	Watching (JOI13_watching)	C++14	100 / 100	809 ms	20980 KiB

watching

#include <bits/stdc++.h>
 
using namespace std;
 
const int N = 2202;
 
int n, p, q;
int a[N];
int f[N][N];
 
int one[N];
int two[N];

int main(){
	if(fopen("1.inp", "r")){
		freopen("1.inp", "r", stdin);
	}
 
	scanf("%d%d%d", &n, &p, &q);
 
	for(int i = 1; i <= n; ++i){
		scanf("%d", a + i);
	}
 
	p = min(p, n);
	q = min(q, n);
 
	sort(a + 1, a + n + 1);
 
	int low = 1, high = 1e9, ans = 1e9;
 
	while(low <= high){
		int w = (low + high) >> 1;
	
		for(int i = 0; i <= n; ++i){
			for(int j = 0; j <= n; ++j){
				f[i][j] = 1e9;
			}
		}
		f[0][0] = 0;
 
		bool ok = false, debug = false;
 
		int pterOne = 0, pterTwo = 0;

		for(int i = 1; i <= n; ++i){
			while(a[i] - a[pterOne + 1] + 1 > w) ++pterOne;
			while(a[i] - a[pterTwo + 1] + 1 > w + w) ++pterTwo;
			
			one[i] = pterOne; 
			two[i] = pterTwo;				
		}

			
		for(int j = 0; j <= p; ++j){
 

			for(int i = 1; i <= n; ++i){


				if(j > 0) f[i][j] = min(f[i][j], f[one[i]][j - 1]);
				f[i][j] = min(f[i][j], f[two[i]][j] + 1);
				
 
				if(i == n && f[i][j] <= q){
					ok = true;
					break;
				}
			}
			if(ok) break;
		}
 
 
		if(ok == false){
			low = w + 1;
		}
		else{
			ans = w;
			high = w - 1;
		}
	}
 
	cout << ans;
 
	return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:42:20: warning: unused variable 'debug' [-Wunused-variable]
   bool ok = false, debug = false;
                    ^
watching.cpp:16:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen("1.inp", "r", stdin);
                               ^
watching.cpp:19:29: 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:22:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", a + i);
                     ^

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