Submission #5370264

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;

#define lint long long
#define P pair<int, int>
#define LLP pair<long long, long long>
#define REP(i, x, n) for(int i = (x), i##_len = (int)(n) ; i < i##_len ; ++i)
#define rep(i, n) for(int i = 0, i##_len = (int)(n) ; i < i##_len ; ++i)
#define reps(i, n) for(int i = 1, i##_len = (int)(n) ; i <= i##_len ; ++i)
#define rrep(i, n) for(int i = (int)(n) - 1 ; i >= 0 ; --i)
#define rreps(i, n) for(int i = (int)(n) ; i > 0 ; --i)
#define SORT(x) sort((x).begin(), (x).end())
#define SORT_INV(x) sort((x).rbegin(), (x).rend())

const int IINF = (1 << 30) - 1;
const long long LLINF = 1LL << 61;
const long long MOD = 1000000007LL;
const int dx4[] = {1, 0, -1, 0}, dy4[] = {0, 1, 0, -1};
const int dx8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dy8[] = {0, -1, -1, -1, 0, 1, 1, 1};
const double EPS = 1e-8;

int n;
vector<lint> a;
int memo[2][1001];

template<typename T>
bool chmax(T &_a, T _b){
    if(_a < _b){
        _a = _b;
        return true;
    }else{
        return false;
    }
}

template<typename T>
bool chmin(T &_a, T _b){
    if(_a > _b){
        _a = _b;
        return true;
    }else{
        return false;
    }
}

int solve(int t, int k, const lint mid){
    if(k == n){
        return 0;
    }else if(memo[t][k] >= -2000){
        return memo[t][k];
    }

    int res;
    lint val = 0;
    if(t == 0){
        res = -2000;
        REP(i, k, n){
            val += a[i];
            if(val >= mid){
                chmax(res, solve(1, i + 1, mid) + 1);
            }else{
                chmax(res, solve(1, i + 1, mid) - 1);
            }
        }
    }else{
        res = 2000;
        REP(i, k, n){
            val += a[i];
            if(val >= mid){
                chmin(res, solve(0, i + 1, mid) + 1);
            }else{
                chmin(res, solve(0, i + 1, mid) - 1);
            }
        }
    }

    return memo[t][k] = res;
}

bool check(long long mid){
    fill(memo[0], memo[2], -3000);
    return solve(0, 0, mid) >= 0;
}

long long meguru_search(long long ok, long long ng){
    while(abs(ok - ng) > 1LL){
        long long mid = (ok + ng) / 2LL;
        if(check(mid)){
            ok = mid;
        }else{
            ng = mid;
        }
    }
    return ok;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    cin >> n;

    a.resize(n);
    rep(i, n){
        cin >> a[i];
    }

    lint ans = meguru_search(-1e13, 1e13);
    cout << ans << endl;

    return 0;
}

Submission Info

Judge Result