Submission #240616

#	Time	Username	Problem	Language	Result	Execution time	Memory
240616		mhy908	Feast (NOI19_feast)	C++14	100 / 100	177 ms	12280 KiB

feast

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef pair<LL, LL> pll;
const LL llinf=10000000000000;

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

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

int main(){
    dp[0][0]=-llinf, dp[0][1]=0;
    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:23:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &k);
     ~~~~~^~~~~~~~~~~~~~~~~
feast.cpp:25:14: 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: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29