Submission #240609

#	Time	Username	Problem	Language	Result	Execution time	Memory
240609		mhy908	Feast (NOI19_feast)	C++14	4 / 100	148 ms	12072 KiB

feast

#include <bits/stdc++.h>
#define eb emplace_back
#define mp make_pair
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define svec(x) sort(x.begin(), x.end())
#define press(x) x.erase(unique(x.begin(), x.end()), x.end())
#define lb(x, v) lower_bound(x.begin(), x.end(), v)
#define ub(x, v) upper_bound(x.begin(), x.end(), v)
using namespace std;
typedef long long LL;
typedef pair<int, int> pii;
typedef pair<LL, LL> pll;
typedef pair<int, LL> pil;
typedef pair<LL, int> pli;
const LL llinf=10000000000000;
const LL mod1=1000000007;
const LL mod2=998244353;
const int inf=2000000000;

int n, k;
LL arr[300010], dp[300010][2], cnt[300010][2];

int solve(LL x){
    dp[0][0]=-llinf;
    dp[0][1]=0;
    for(int i=1; i<=n; i++){
        if(dp[i-1][0]>dp[i-1][1]-x)dp[i][0]=dp[i-1][0]+arr[i], cnt[i][0]=cnt[i-1][0];
        else dp[i][0]=dp[i-1][1]+arr[i]-x, cnt[i][0]=cnt[i-1][1]+1;
        tie(dp[i][1], cnt[i][1])=max(tie(dp[i-1][0], cnt[i][0]), tie(dp[i-1][1], cnt[i][1]));
    }
    if(dp[n][0]>dp[n][1])return cnt[n][0];
    return cnt[n][1];
}

int main(){
    scanf("%d %d", &n, &k);
    for(int i=1; i<=n; i++){
        scanf("%lld", &arr[i]);
        arr[i]*=2;
    }
    LL l=0, r=llinf;
    while(l<r){
        LL mid=(l+r)/2;
        if(solve(mid*2+1)>=k)l=mid+1;
        else r=mid;
    }
    solve(l*2);
    printf("%lld", max(dp[n][0], dp[n][1])/2+l*k);
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:38:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &k);
     ~~~~~^~~~~~~~~~~~~~~~~
feast.cpp:40:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld", &arr[i]);
         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 0 / 8
• Subtask 3: 0 / 18
• Subtask 4: 0 / 10
• Subtask 5: 0 / 11
• Subtask 6: 0 / 20
• Subtask 7: 0 / 29