Submission #441570

#	Time	Username	Problem	Language	Result	Execution time	Memory
441570		leaked	Bigger segments (IZhO19_segments)	C++14	37 / 100	1587 ms	4172 KiB

segments

#include <bits/stdc++.h>
 
#define vec vector
#define sz(x) (int)x.size()
#define m_p make_pair
#define f first
#define s second
 
using namespace std;
 
typedef long long ll;
typedef pair<ll,int> pli;
typedef pair<int,ll> pil;
auto rng=bind(uniform_int_distribution<int>(1,1e9),mt19937(time(0)));
template<class T> bool umax(T &a,const T &b){return (a<b?a=b,1:0);}
template<class T> bool umin(T &a,const T &b){return (a>b?a=b,1:0);}
int brute(vec<int> a){
    int n=sz(a);
    vec<vec<int>>dp(n,vec<int>(n,-2*n));
    vec<ll>pref(n,0);
    for(int i=0;i<n;i++) pref[i]=(i?pref[i-1]:0)+a[i];
    auto get=[&](int l,int r){
        return pref[r]-(l?pref[l-1]:0);
    };
    int ans=0;
    for(int i=0;i<n;i++){
        umax(dp[0][i],1);
        for(int j=0;j<=i;j++){
            for(int k=i+1;k<n;k++){
                if(get(i+1,k)>=get(j,i)){
                    umax(dp[i+1][k],dp[j][i]+1);
                }
            }
//            cout<<i<<' '<<j<<endl;
            umax(ans,dp[j][i]);
        }
    }
    return ans;
}
int stupid(vec<int> a){
    int n=sz(a);
    vec<ll>pref(n,0);
    for(int i=0;i<n;i++) pref[i]=(i?pref[i-1]:0)+a[i];
    auto get=[&](int l,int r){
        return pref[r]-(l?pref[l-1]:0);
    };
    int ans=0;
    vec<pil>dp(n,m_p(-2*n,-2*n));
    for(int i=0;i<n;i++){
        dp[i]=m_p(1,-get(0,i));
        for(int j=0;j<i;j++){
            if(get(j+1,i)>=-dp[j].s){
                umax(dp[i],m_p(dp[j].f+1,-get(j+1,i)));
            }
        }
      	if(i) assert(dp[i].f>=dp[i-1].f);
        umax(ans,dp[i].f);
    }
    return ans;
}
signed main(){
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int n;
    cin>>n;
//    cout<<n<<endl;
    vec<int>a(n);
    vec<ll>pref(n);
    for(auto &z : a) cin>>z;
//    cout<<endl;
//    cout<<brute(a);
//    return 0;
    for(int i=0;i<n;i++){
        pref[i]=(i?pref[i-1]:0)+a[i];
    }
    auto get=[&](int l,int r){
        return pref[r]-pref[l-1];
    };
    ll lst=a[0],s=0;
    int cnt=1;
    int w=0;
 
    for(int i=1;i<n;i++){
        s+=a[i];
        if(s>=lst){
            int j=w;
            while(1){
                if(pref[i]-pref[j]<pref[j]-pref[w]+lst) break;
                j++;
            }
            j--;
            cnt++;
            lst=pref[i]-pref[j];
            w=i;
            s=0;
        }
    }
//    assert(stupid(a)==brute(a));
    cout<<stupid(a);
//    assert(cnt==brute(a));
////    cout<<cnt<<endl;
//    }
    return 0;
}
 
/*
10
2 1 2 2 1 1 3 2 5 5
*/

Compilation message (stderr)

segments.cpp: In function 'int main()':
segments.cpp:75:10: warning: variable 'get' set but not used [-Wunused-but-set-variable]
   75 |     auto get=[&](int l,int r){
      |          ^~~

• Subtask 1: 13 / 13
• Subtask 2: 14 / 14
• Subtask 3: 10 / 10
• Subtask 4: 0 / 36
• Subtask 5: 0 / 27