提出 #17915750

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ソースコード 拡げる

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
constexpr int Inf = 1000000030;
constexpr ll INF= 2000000000000000000;
constexpr ll MOD = 998244353;
const double PI = 3.1415926535897;
typedef pair<int,int> P;
typedef pair<int,P> PP;

template<class T> inline bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}

template<class T> inline bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return 1;
    }
    return 0;
}

ll mod(ll val, ll M) {
    val = val % M;
    if(val < 0) {
        val += M;
    }
    return val;
}

template<typename T>
T RS(T N, T P, T M){
    if(P == 0) {
        return 1;
    }
    if(P < 0) {
        return 0;
    }
    if(P % 2 == 0){
        ll t = RS(N, P/2, M);
        if(M == -1) return t * t;
        return t * t % M;
    }
    if(M == -1) {
        return N * RS(N,P - 1,M);
    }
    return N * RS(N, P-1, M) % M;
}

int N;
ll vec[4010];
ll dp[4010][4010];

ll solve(int i,int j) {
    if(i > j) return 0;
    if(dp[i][j] != -1) return dp[i][j];
    if((N - (j - i + 1)) % 2 == 0) {
        return dp[i][j] = max(solve(i + 1,j) + vec[i],solve(i,j - 1) + vec[j]);
    }
    else {
        if(vec[i] > vec[j]) return dp[i][j] = solve(i + 1,j);
        return dp[i][j] = solve(i,j - 1);
    }
}

int main() {
    cin >> N;
    for(int i = 0;i < N;i++) {
        int A;
        cin >> A;
        vec[i] = A;
        vec[i + N] = A;
    }
    for(int i = 0;i < 4010;i++) {
        for(int j = 0;j < 4010;j++) {
            dp[i][j] = -1;
        }
    }
    ll ret = 0;
    for(int i = 0;i < N;i++) {
        chmax(ret,solve(i,i + N - 1));
    }
    cout << ret << endl;
}

提出情報

ジャッジ結果