Submission #320552

#	Time	Username	Problem	Language	Result	Execution time	Memory
320552		arnold518	Sparklers (JOI17_sparklers)	C++14	0 / 100	1 ms	492 KiB

sparklers

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

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 1000;
const ll INF = 1e18;

int N, K;
ll T, A[MAXN+10], B[MAXN+10];

bool dp[MAXN+10][MAXN+10];

bool decide(ll X)
{
	X*=2;
	//if(T*X>(ll)1e9) return true;
	for(int i=1; i<=N; i++) B[i]=A[i]-i*T*X;
	//for(int i=1; i<=N; i++) printf("%lld ", A[i]); printf(" : %lld\n", X);

	for(int r=1; r<=N; r++) for(int l=r; l>=1; l--)
	{
		if(l==r)
		{
			if(l==K) dp[l][r]=1;
			else dp[l][r]=0;
		}
		else
		{
			dp[l][r]=dp[l+1][r]|dp[l][r-1];
			if(B[l]<B[r]) dp[l][r]=0;
		}
	}
	return dp[1][N];

	int l=K, r=K;
	ll lv=B[l], rv=B[r];
	while(!(l==0 && r==N+1))
	{
		int bl=l, br=r;
		lv=-INF;
		for(; l>=1 && B[l]>=rv; l--) lv=max(lv, B[l]);
		rv=INF;
		for(; r<=N && B[r]<=lv; r++) rv=min(rv, B[r]);
		//printf("%d %d\n", l, r);
		if(l==bl && r==br) return false;
		l++; r--;
	}
	//printf("WOW %lld\n", X);
	return true;
}

int main()
{
	scanf("%d%d%lld", &N, &K, &T);
	for(int i=1; i<=N; i++) scanf("%lld", &A[i]);

	ll lo=0, hi=1e9+10;
	while(lo+1<hi)
	{
		ll mid=lo+hi>>1;
		if(decide(mid)) hi=mid;
		else lo=mid;
	}
	printf("%lld\n", hi);
}

Compilation message (stderr)

sparklers.cpp: In function 'int main()':
sparklers.cpp:63:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   63 |   ll mid=lo+hi>>1;
      |          ~~^~~
sparklers.cpp:57:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   57 |  scanf("%d%d%lld", &N, &K, &T);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sparklers.cpp:58:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   58 |  for(int i=1; i<=N; i++) scanf("%lld", &A[i]);
      |                          ~~~~~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50