Submission #1017473

#	Time	Username	Problem	Language	Result	Execution time	Memory
1017473		vjudge1	Feast (NOI19_feast)	C++14	100 / 100	112 ms	14012 KiB

feast

#include <bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define taskname ""
using namespace std;
ll n,k,i,l,r,mid,answer=-1e18,dp[300009][2],a[300009],cnt[300009][2],sum;
pll ans;
pll check(ll v){
        dp[1][0]=0;
        dp[1][1]=a[1]-v;
        cnt[1][0]=0;
        cnt[1][1]=1;
    for(i=2;i<=n;i++){
        if(dp[i-1][1]<dp[i-1][0]){
            dp[i][0]=dp[i-1][0];
            cnt[i][0]=cnt[i-1][0];
        }else{
            dp[i][0]=dp[i-1][1];
            cnt[i][0]=cnt[i-1][1];
        }
        if(dp[i-1][1]+a[i]<dp[i-1][0]+a[i]-v){
            dp[i][1]=dp[i-1][0]+a[i]-v;
            cnt[i][1]=cnt[i-1][0]+1;
        }else{
            dp[i][1]=dp[i-1][1]+a[i];
            cnt[i][1]=cnt[i-1][1];
        }
    }pll res={dp[n][1],cnt[n][1]};
    pll result={dp[n][0],cnt[n][0]};
    res=max(res,result);
    return res;
}
int main() {
	if (fopen(taskname".inp","r")) {
		freopen(taskname".inp","r",stdin);
		freopen(taskname".out","w",stdout);
	}
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
    cin>>n>>k;
    for(i=1;i<=n;i++)
        cin>>a[i];
    l=0;r=1e18;
    while(l<=r){
        mid=(l+r)/2;
        ans=check(mid);
        if(ans.se<=k){
            answer=max(answer,ans.fi+mid*ans.se);
            r=mid-1;
        }else l=mid+1;
    }cout<<answer;
	return 0;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:40:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |   freopen(taskname".inp","r",stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:41:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |   freopen(taskname".out","w",stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29