제출 #847566

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
847566		BamshooT	Feast (NOI19_feast)	C++14	100 / 100	118 ms	14584 KiB

feast

#include <iostream>
#include <algorithm>
#include <vector>
#include <math.h>
#include <cstdlib>

#define ll long long
#define FOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define inf -1e18
#define fi first
#define se second

using namespace std;

typedef pair <ll, int> li;

const int N = 3e5 + 9, M = 2e3 + 9;
int n, k;
ll a[N], pre[N], dp[M][M];

void sub1(){

    for (int i = 1; i <= k; ++i){
        ll cur = 0;
        for (int j = 1; j <= n; ++j) {
            cur = max(cur, dp[i-1][j] - pre[j]);
            dp[i][j] = max(dp[i][j-1], cur + pre[j]);
        }
    }
    cout << dp[k][n];
}

pair<ll, int> f[N];

void maximize(li &a, li b){
    if (a.fi < b.fi) a = b;
    if (a.fi == b.fi && a.se > b.se) a = b;
}

li calc(ll cost){
    li best = {0, 0};
    for (int i = 1; i <= n; ++i) {
        f[i] = f[i-1];
        maximize(f[i], {pre[i] + best.fi - cost , best.se + 1});
        maximize(best, {f[i].fi - pre[i], f[i].se});
    }
    //f[n].se *= -1;
    return f[n];
}

/// code WA
void sub2(){
    ll lo = -1e18, hi = 1e18, ans = 0;
    while (lo <= hi) {
        ll mid = lo + hi >> 1;
        li tmp = calc(mid);
        if (tmp.se <= k) {
            hi = mid - 1;
            ans = max(ans, tmp.fi + mid*tmp.se);
        } else lo = mid + 1;
    }
    cout << ans;
}

/// code AC
//void sub2(){
//    ll lo = -1e18, hi = 1e18, ans = 0;
//    while (lo < hi) {
//        ll mid = lo + hi >> 1;
//        li tmp = calc(mid);
//        if (tmp.se <= k) {
//            hi = mid;
//        } else lo = mid + 1;
//    }
//    li tmp = calc(lo);
//    cout << tmp.fi + k*lo;
//}

int main(){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
   // freopen("nhap.inp", "r", stdin);
   // freopen("xuat.out", "w", stdout);
    cin >> n >> k;
    FOR(i, 1, n) {
        cin >> a[i];
        pre[i] = pre[i-1] + a[i];
    }
   // if (max(k, n) <= 2000) sub1(); else
    sub2();
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

feast.cpp: In function 'void sub2()':
feast.cpp:55:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   55 |         ll mid = lo + hi >> 1;
      |                  ~~~^~~~

• 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