Submission #237728

#	Time	Username	Problem	Language	Result	Execution time	Memory
237728		Half	Feast (NOI19_feast)	C++14	30 / 100	220 ms	125560 KiB

feast

#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <cmath>

using namespace std;

typedef vector<int> vi;
typedef pair<int,int> pi;
typedef long long ll;

#define loop(i,a,b) for (int i = a; i <= b; i++)

#define INF ((unsigned) ~0)
#define F first
#define S second
#define PB push_back
#define MP make_pair

const int MXN = 500000;
int N, K;
int a[MXN];
vector<ll> g;
vector<ll> sg;
ll mem[4000][4000];

int dp(int l, int n){
    if(l >= g.size())
        return 0;
    if(n <= 0)
        return 0;
    if(mem[l][n] != -1)
        return mem[l][n];
    ll sol = sg[l + 1] - sg[l];
    for(int i = l + 1; i <= g.size(); i++)
        for(int j = l; j <= i; j++)
            sol = max(sol, dp(i, n - 1) + sg[i] - sg[j]);
    mem[l][n] = sol;
    return sol;
}

int main(){
    cin >> N >> K;
    for(int i = 0; i < N; i++){
        cin >> a[i];
        if(g.size() == 0){
            g.push_back(a[i]);
        }else if((g[g.size() - 1] >= 0 && a[i] >= 0) || (g[g.size() - 1] < 0 && a[i] < 0)){
            g[g.size() - 1] += a[i];
        }else{
            //cout << g[g.size() - 1] << " ";
            g.push_back(a[i]);
        }
    }
    //cout << "\n";
    ll sm = 0;
    sg.push_back(0);
    for(int i = 0; i < g.size(); i++){
        sm += g[i];
        sg.push_back(sm);
    }
    if(g.size() == 1){
        cout << sm << "\n";
    }else if(g.size() == 2){
        cout << max(g[0], g[1]) << "\n";
    }else if(g.size() == 3 && g[0] > 0){
        if(K == 1)
            cout << max(max(g[0], g[2]), g[0] + g[1] + g[2]) << "\n";
        if(K >= 2)
            cout << g[0] + g[2] << "\n";
    }else if(K == 1){
        ll mx = 0;
        ll mxEnd = 0;
        for(int i = 0; i < g.size(); i++){
            mxEnd = max(mxEnd + g[i], g[i]);
            mx = max(mx, mxEnd);
        }
        cout << mx << "\n";
    }else{
        for(int i = 0; i < 4000; i++)
            for(int j = 0; j < 4000; j++)
                mem[i][j] = -1;
        cout << dp(0, N) << "\n";
    }
}

Compilation message (stderr)

feast.cpp: In function 'int dp(int, int)':
feast.cpp:30:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(l >= g.size())
        ~~^~~~~~~~~~~
feast.cpp:37:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = l + 1; i <= g.size(); i++)
                        ~~^~~~~~~~~~~
feast.cpp: In function 'int main()':
feast.cpp:60:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < g.size(); i++){
                    ~~^~~~~~~~~~
feast.cpp:76:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0; i < g.size(); i++){
                        ~~^~~~~~~~~~

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