Submission #68311

#	Time	Username	Problem	Language	Result	Execution time	Memory
68311		thebes	Watching (JOI13_watching)	C++14	100 / 100	513 ms	16668 KiB

watching

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

const int MN = 2002;
int pos[MN], N, P, Q, i, lo, hi, l, r, k, nxt[MN], nxt2[MN], dp[MN][MN];
int solve(int n,int rem){
	if(n == N+1) return 0;
	else if(dp[n][rem]!=-1) return dp[n][rem];
	if(rem) dp[n][rem]=min(solve(nxt[n],rem-1),solve(nxt2[n],rem)+1);
	else dp[n][rem]=solve(nxt2[n],rem)+1;
	return dp[n][rem];
}
bool check(int w){
	for(l=r=k=1;l<=N;l++){
		while(r<=N&&pos[r]-w+1<=pos[l]) r++;
		while(k<=N&&pos[k]-2*w+1<=pos[l]) k++;
		nxt[l] = r; nxt2[l] = k;
	}
	memset(dp, -1, sizeof(dp));
	return solve(1,P)<=Q;
}
int main(){
	for(scanf("%d%d%d",&N,&P,&Q),i=1;i<=N;i++)
		scanf("%d",&pos[i]);
	P = min(P, N);
	sort(pos+1,pos+N+1);
	lo = 1, hi = 1e9+7;
	while(lo < hi){
		int m = lo+hi>>1;
		if(check(m)) hi=m;
		else lo=m+1;
	}
	printf("%d\n",hi);
	return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:29:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int m = lo+hi>>1;
           ~~^~~
watching.cpp:23:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(scanf("%d%d%d",&N,&P,&Q),i=1;i<=N;i++)
      ~~~~~~~~~~~~~~~~~~~~~~~~^~~~
watching.cpp:24:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&pos[i]);
   ~~~~~^~~~~~~~~~~~~~

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